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Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2010, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2010, Bu tez kapsamında kontrolsüz dolgu zeminde uygulanan zemin çivili duvar örnekleri için tasarıma esas alınan zemin mukavemet parametreleri ve sahada ölçülen deplasman değerleri kullanılarak zeminin deformasyon parametreleri geri analiz ile elde edilmiştir. Literatürde mevcut zemin çivili duvar hesap esasları limit denge analizlerine dayanmakta ve deformasyon tahminleri açısından eksiklikler içermektedir. Bu sebeple deformasyon analizlerinde sayısal modelleme yöntemlerine dayalı bir sonlu elemanlar programı tercih edilmiştir. Literatüre dayalı deformasyon tahminleri sahada ölçülen değerler ile karşılaştırılmıştır. Bu analizde kullanılan zemin parametreleri seçimi ve zemin çivili duvar elemanlarının rijitlik özelliklerinin hesap yöntemleri anlatılmıştır. İncelenen iksa kesitlerinin performans değerlendirmeleri çivi boyları ve çivi yoğunluklarını içerecek şekilde detaylı olarak açıklanmıştır., In the scope of this thesis, a soil nailed wall on a non-controlled fill is evaluated. The soil deformation parameters have been achieved via back analysis by using soil strength parameters which formed the basis for design, and the deformation values measured at site. Their calculation principle is based on limit equilibrium analysis. Therefore their deformation estimations do not provide exact figures. Hence, in their deformation analysis, finite element program is used as a numeric modelling method. Measured deformations are compared with deformation estimations based. Determination of soil parameters and calculation of strength parameters of soil nail wall components are defined. Performance analysis of observed retaining wall sections are interpreted including nail lengths and nail density., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2009, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2009, Bu çalışmada, yumuşak zeminler üzerindeki geosentetikle güçlendirilmiş kazıkla desteklenmiş dolguların analizinde yer alan yük aktarma mekanizmalarının incelenebilmesi için İngiliz Standardı BS 8006 (1995), Alman Standardı EBGEO (2004) (Tasarı) ve sonlu eleman analiz programı Plaxis 3D Foundation kullanılmıştır. Geosentetikle güçlendirilmiş kazıkla desteklenmiş dolguların yük aktarma mekanizmalarından biri olan kemerlenme, seçilen bu iki standart ve Plaxis 3D Foundation programı ile üç boyutlu olarak ele alınabilmektedir. Söz konusu standartlarda yer alan analiz yöntemlerine göre sürşarj ve dolgu yüklerinin kazıklara, geosentetik donatıya ve yumuşak zemine aktarılma mekanizmaları incelenerek sabit yumuşak zemin derinliğinde dolgu yüksekliği, kazık çapı ve kazıklar arası mesafenin farklı değerlerinin kazık etkinliği ve gerilme konsantrasyon oranına etkileri araştırılmıştır. Plaxis programı ile yapılan analizlerde ise yukarıda bahsedilen değişken parametrelerin yanısıra yumuşak zeminin farklı derinlik değerlerinin kazık etkinliği, gerilme konsantrasyon oranı ve deplasman değerlerine olan etkileri incelenmiştir. Gerilme konsantrasyon oranının değişimine göre zemin kemerlenmesini değerlendirmek mümkündür. Dolayısıyla kullanılan değişken parametrelerin zemin kemerlenmesi üzerine etkileri de incelenmiştir., In this study, in order to examine load transfer mechanisms in the analysis of geosynthetic reinforced pile supported embankments over soft soils, British Standard BS 8006 (1995), German Standard EBGEO (2004) (Draft) and finite element analysis program Plaxis 3D Foundation have been used. Soil arching, which is one of the load transfer mechanisms of geosynthetic reinforced pile supported embankments, can be considered as three dimensional with those standards and Plaxis 3D Foundation program. According to the analysis methods in the standards, by examining transfer mechanism of surcharge and embankment loads to piles, geosynthetic reinforcement and soft soil, effects of different values of embankment height, pile diameter and distance between pile centers on pile efficiency and stress concentration ratio have been investigated in the fixed depth of soft soil. In the analysis which have been done with Plaxis 3D Foundation program, beside the variable parameters mentioned above effects of different depth values of soft soil on pile efficiency, stress concentration ratio and displacement values have been investigated. It is possible to evaluate the soil arching according to the variation of stress concentration ratio. Because of that, effects of variable parameters used on soil arching have been investigated., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2008, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2008, Bu çalısmada; derin kazılarda uygulanan çok sıralı ankrajlı destekleme sistemlerinin, çesitli toprak basıncı dağılımı kabulleri altında davranısının incelenmesi için Đksa2008 adlı bilgisayar programı gelistirilmistir. Excel ve Visual Basic Entegrasyonu ile programlama dili kullanılarak gelistirilen programda, iksa sistemlerinin, tasarımında kullanılan teori ve hesap yöntemlerine dayanarak, iksa sisteminin iki boyutlu olarak modellenip sonlu elemanlar yöntemi ile çözülüp, gerekli stabilite tahkikleri yapılarak boyutlandırılması sağlanmıstır. İksa2008 programı kullanılarak farklı zemin tabakalarında iksa sistemi modellenmis ve iki ayrı analiz yapılmıstır. 1 nolu analizde, farklı zemin tabakalarında, 15m kazı derinliğinde, 4 sıra ankraj ile desteklenen bir iksa sistemi modellenmis ve iksa sistemi çözümü değisik toprak basıncı dağılımı kabulleri için tekrarlanmıstır. Bilgisayar programı ile yapılan 2 nolu analizde farklı kazı derinliklerinde değisik sayıda ankraj ile desteklenen iksa sistemi modellenmistir. İksa sistemi modelinin, her bir ankraj kademesi için ayrı analizi yapılmıs olup, sistemde olusan moment, kesme kuvveti, yerdeğistirme ve ankraj kuvvet değerleri hesaplanmıstır. Bu değerlerin çesitli toprak basıncı dağılımları altında ankraj kademeleri arası değisimi grafiksel olarak yorumlanmıstır., In this study, Iksa2008 Finite Element computer program is developed to analyze the behavior of multiple anchored shoring systems under various soil pressure distribution assumptions is determined by using Đksa2008 computer program. Developed computer program using the programming language with integration of Excel and Visual Basic, is based on the teorical and calculation methods of shoring systems design. The model of shoring system is created as two dimension by the finite element method and analysed. The elements of system is designed afterwards checking stability failure mechanisim. Shoring system is designed through various soil layers by using Đksa2008 program and two analysis presented. Deep excavation, 15 meter depth through different soil, supported with 4 row anchors is designed and the analysis of model is recalculated for various assumption of lateral soil pressures in the analysis no 1. Second analysis about different depth of deep excavation supported by varied anchor row and recalculation for each anchor stage to get maximum value of bending moment, shear stress, deflection and anchor stress. The diagrams present the change of these values accordance with the anchor stage is given., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2008, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2008, Yapılan bu çalışmada belirli şartnamelerin esaslarına göre EXCEL programı ile çeşitli sıvılaşma analizi yöntemlerinin birlikte değerlendirildiği bir program hazırlanmıştır., In this study, by using the standarts, and by using the EXCEL programme, liquefaction analyses programmed which evaluates various liquefaction criteria., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2007, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2007, Bu tez çalışmasının amacı, sonlu elemanlar yöntemi kullanılarak perde kazıkların modellenmesi, farklı çaplar ve farklı aralıklarda kazıkların dizaynı ve karşılaştırmalı olarak yorumlanmasından oluşmaktadır. Plaxis 3D Foundation Sonlu Elemanlar Programı kullanılarak perde kazıklar için üç boyutlu modeller ile analizler yapılmıştır. Genel olarak 3D Foundation modeller ön kısmındaki zemini kazılmış bir sıra kazıktan oluşmaktadır. Analizlerde kullanılan çeşitli kazık çapları ile kazıklar arasındaki mesafenin taşıma gücüne etkisi (grup etkisi) incelenmiştir. Ayrıca kazık modelleri iki farklı zemin (kum ve kil) için dizayn edilmiş ve kendi içlerinde farklılık gösterdiği için ayrı ayrı karşılaştırılmıştır. Nümerik analizlerin yanında kazıkların taşıma gücü ve kazık grupları hakkında literatür bilgileri yer almıştır. Sonlu elemanlar yöntemiyle yapılan modellerde kazık taşıma gücü ve grup etkisinin gerçeğe uygunluğu görülmüştür. Sonuç bölümünde ise; yapılan analizler hakkında yorumlar yapılmış ve ortaya çıkan sonuçlar hakkında değerlendirmelerde bulunulmuştur., The purpose of this thesis study consists of the modeling of the pile walls by using the method of finite elements, design of the piles in different diameters and in different halls and comperative observation (commentary). Analysis has been done with three dimensional models for the pile walls by using the Plaxis 3D Foundation Finite Elements Programme. Generally 3D Foundation models consist of one raw pile which its ground on the front part was excavated. The effect of the distance between the different pile diameters that are used in the analysis and the distance between the piles to the bearing capacity (group effect) was analyzed. Furthermore, the pile models are designed for two different grounds (sand and clay) and they are compared separately as they differ between themselves. Apart from the numerical analysis, the bearing capacity of the piles and literature information about the pile groups take part. The bearing capacity of the piles is explained with the finite elements method and group effect. In the conclusion part, commented on the analysis done and evaluations are done about the results that came out., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2006, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2006, Hazırlanan bu yüksek lisans tezinde, son yıllarda ülkemizde de geniş uygulama alanı bulan zemin çivili duvarlar hakkında detaylı bilgi verilmiştir. Zemin çivisi tekniği, zemine sık aralıklarla pasif takviyeler yerleştirerek mevcut zeminin yerinde güçlendirilmesini sağlamaktadır. Zemin çivili duvarlar, diğer klasik sistemlerden daha hızlı uygulanabilmesi ve ekonomik olması sebebiyle sıkça tercih edilen ve uygulanan bir yöntem haline gelmiştir. Çalışma kapsamında, zemin çivisi tekniği ile ilgili detaylı bir literatür araştırması yapılmış, eğimli yüzeylerde zemin çivisi uygulamasında göz önüne alınacak unsurlara yer verilmiştir. Zemin çivili istinat yapıları tasarımında kullanılan parametreler olan zemin parametrelerinin, geometrik parametrelerin ve tasarım yaklaşımlarının, hesapları ne şekilde etkilediği incelenmiştir. Bu amaca yönelik olarak, Excel kullanılarak oluşturulmuş bir hesap programı kullanılmıştır. Bu program FHWA tarafından zemin çivili duvar hesabı için hazırlanan FHWA-SA-96-096R şartnamesini temel alarak, şartnamenin içerdiği her iki tasarım yöntemiyle (Servis Yükü Tasarımı ve Yük ve Dayanım Katsayıları Tasarımı) birden hesap yapmaktadır. Böylece, aynı zamanda, iki tasarım yöntemini de karşılaştırma imkanı sunmaktadır., In this thesis study, comprehensive information was presented about soil nailing technique which has also found broad application range in the recent years in our country. With soil nailed walls, existing ground is being reinforced and used effectively by installing passive bars with close spacing. Soil nailing walls have often become a preferred method since it is economical and can be applied faster than other classical systems. Detailed research in literature was conducted on soil nailing technique, design of soil nailed walls in inclined surfaces were included within the scope of this thesis study. The effect of the soil paramaters, geometrical parameters and the design methods that are used in the design of the soil nailed retaining wall is also investigated. For this purpose, an excel dominated calculation programme is used. In this programme the FHWA-SA-96-096R specifications (both the Service Load Design and Load & Resistance Factor Design techniques) which is prepared for soil nailed retaining wall calculations is used., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2006, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2006, Hazırlanan bu yüksek lisans tezinde, ilk olarak kazıklarda negatif çevre sürtünmesi hakkında genel anlamda bilgi verilirken, kazıklı temel türleri ve kazık tipi seçimine etkiyen faktörler incelenmiş ve kazıklı temellerin dayanımı üzerinde durulmuştur. Sonraki bölümde, kazıklarda çevre sürtünmesi ele alınmış, özellikle kil zeminlerde çevre sürtünmesi irdelenmiş ve kohezyonlu zeminlerde teşkil edilen kazıklar hakkında bilgi verilmiştir. Bir diğer bölümde tezin ana konusunu oluşturan negatif çevre sürtünmesini meydana getiren faktörler ve negatif çevre sürtünmesinin kazık boyunca dağılımı incelenmiş, negatif çevre sürtünmesi problemi konu edilmiştir. Aynı zamanda, çeşitli bilim adamlarının negatif çevre sürtünmesi ile ilgili çalışmalarından, negatif çevre sürtünmesi hesap yöntemlerinden ve bu etkiyi azaltmak için yapılan deney ve çalışmalardan bahsedilmiştir. Tezin son kısmında ise tek bir kazığa gelen negatif çevre sürtünmesi sonlu elemanlar programı PLAXIS’ te hesaplanmış ve yapılan bu çalışma sonucunda ortaya çıkan sonuçlar değerlendirilmiştir., In this thesis, after the first chapter which introduces the problem, the skin friction of piles is investigated in general and the types and resistance of piles and the factors of pile’ s selection is mentioned. Then, stress conditions in a soil element adjacent to the pile shaft is studied and Mohr-Coulomb failure envelopes are given for different stress conditions. In these analysis, normally consolidated and over-consolidated clays are considered separately. It is emphasized that the amount of friction angle mobilized or assumed between the soil and the pile material highly affects the stress the stress conditions and the mobilized positive skin friction. The general static formula for ultimate pile capacity is also studied. Negative skin friction problem is studied in other chapter, piles characteristics and soil properties those affecting and soil properties those affecting the negative skin friction are reported. The distribution of negative skin friction along the pile shaft for the piles resting on a non-compressible stratum and piles terminating in a compressible soil layer are investigated. Idealized diagrams of negative skin friction given in the literature are also included in this study. The other chapter deals with the calculation of negative skin friction forces. Techniques available to reduce the drag-down forces are explained in detail. The significance of neutral point on the magnitude of drag-down forces is also emphasized. Finally negative skin friction on piles is analyzed with using finite element program PLAXIS and conclusions are evaluated., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2006, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2006, Kazık tasarımı ve bu tasarım için yapılan hesaplar, bir yapı-zemin etkileşmesi problemidir. Bu etkileşmede kazıkların, tam anlamı ile gerçekçi olmasa da doğrusal elastik davranış gösteren yapı elemanları olarak ele alınmaları, zeminin benzer bir davranış varsayımı ile ele alınmasından daha olağan görünmektedir. Bununla beraber pratik çözümlerde gerek aşırı karmaşık yaklaşımlardan kaçınmak isteği ve gerekse pek çok halde yük altında oluşan küçük deformasyonlar için zemin davranışının da doğrusal olabileceğine dair belge ve gözlemlerin varlığı her iki elaman içinde pek çok halde yük-ötelenme ilişkisinin doğrusal olarak tanımlanması sonucunu doğurmuştur. Çözümlerin bu halde dahi çok basit olmadığı bilinmektedir. Bu çalışmada da bu doğrultuda, düşey yükler altındaki tek ve grup kazıkların davranış esaslarına ve düşey yüklü kazıkların analiz yöntemlerine değinilmiştir. Kazıklar arası ara mesafenin taşıma gücüne etkisini araştırmak için Plaxis 3D Foundation sonlu elamanlar programı ile iki farklı zemin profilinde bir çok analiz yapılmıştır., Pile design is a problem of building-soil interaction. It is more usual assuming the behavior of piles linear elastic than the behavior of soil. The will of avoiding from complex solutions in practice and the existence of the documents and observations about the behavior of the soil like minor deformations in most loading case, leads the linear elastic assumption for both materials. Despite these assumptions solutions are not easy. In this research, the behavior fundamentals of single pile and pile group which are under vertical loads and analysis methods of pile groups which under vertical loads are defined. In order to study the effects of the spacing between piles to bearing capacity, two different analysis for two different soil profile are done with computer program named Plaxis 3D Foundation which uses the method of finite elements., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2006, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2006, Taşıma gücü probleminin aşılması için yapılan kazıklı temeller veya zeminin kazıklarla desteklenmesi gibi uygulamalarda kazık yükleme deneyleri çoğu zaman tasarımın bir parçası olarak işlev görür. Bu çalışmada, kazık yükleme deneylerinin sonuçları ele alınmış ve bu sonuçlar değerlendirilmiştir. Bunun için ilk önce kazıkların sınıflandırılması ve kazıkların taşıma kapasitesinin belirlenmesi ile ilgili genel ilkelere değinilmiştir. Zeminin özellikleri ile kazık arasındaki ilişkilerin önceden tam olarak bilinemeyecek belirsizlikler taşıması, kazıkların bazı deney aşamalarından geçirilmesini gerektirir. Bu belirsizliklerin aşılması amacı ile yapılan deney ve kontrollere üçüncü bölümde değinilmiştir. Bu deneylerden, tezin konusuna esas oluşturan statik eksenel basınç deneyleri, şu amaçlarla yapılır. 1. Kazığın tasarım yükünde yaptığı oturmayı belirlemek 2. Kazığın göçme yükünü belirlemek 3. Tasarımın doğruluğunu kanıtlamak Deney teknikleri, bu deneylerden elde edilen sonuçların kazığın emniyetle taşıyabileceği yükü belirlemekte kullanılacak güvenlik katsayısı üzerindeki etkisi ile yükleme deneylerinin kazık tasarımındaki yeri tartışılmıştır. Deneyde karşılaşılabilecek olumsuzlukların, deneyin değerlendirilmesi üzerindeki etkisi vurgulanmıştır. Bu kapsamda literatürde geçen yöntemlerden Davisson, Brinch Hansen %80, Mazurkiewicz, Chin Kondner, Decourt, Teğet (Mansur Kaufman), Corps of Engineers, De Beer, Brinch Hansen %90, Fuller-Hoy ve Buttler-Hoy yöntemleri ayrıntılı bir şekilde işlenmiştir. Bunlardan Brinch Hansen %90, ve Corps of Engineers yöntemleri haricinde kalan yöntemler, seçilen on adet göçmeye mümkün olduğu kadar yaklaşılmış deneyler üzerinde uygulanmış ve bu değerlendirmelerin sonuçları bir takım istatistik analizlerden geçirilerek tartışılmıştır. Literatür araştırmalarının sonunda kazık yükleme deneylerini değerlendirmek için yeni bir yöntem geliştirilmiş ve bu yöntemin diğer yöntemler ile karşılaştırması yapılmıştır., In the projects of structures that are supported by piles because of the bearing capacity problems, the function of the loading tests of piles, results of these tests, and interpritation of failure load from test results are to be part of the projects. In this study, static axial compression tests and interpritation of failure load from test results are covered. First of all classification of piles and determination of bearing capacity of piles are mensioned. Relationships between the engineering properties of soils and the piles are sometimes can not be well defined because of the inaccuracy of the data obtained from the soil tests or the unknown behaviour of the piles. On this concept, some tests and controlling procedures are applied to the piles. These controlling and testing procedures are mensioned on chapter three. One of these tests which becomes the basis of this study is static axial compression test. Main purposes of static axial compression tests are known as: 1. To determine the settlement under working load of a pile 2. To determine the failure loads of piles 3. To approve the design considerations General test procedures, effects of results from the static axial compression tests on the factor of safety, which is used to determine the allowable load of a pile, and the effects of the static axial compression tests on design process are discussed. Effects of undesirable faults through the test on interpritation of failure load from test data are explained. Davisson, Brinch Hansen 80%, Mazurkiewicz, Chin Kondner, Decourt, Tangent (Mansur Kaufman), Corps of Engineers, De Beer, Brinch Hansen 90%, Fuller-Hoy, and Buttler-Hoy methods are studied. Theese methods acsept Brinch Hansen 90%, and Corps of Engineers methods are applied to predict the failure loads of ten axial compression tests that are picked up from the literature. Results of the methods are expressed and discussed. In addition a new method for interpritating failure load from axial compression load tests of file is developed and discussed., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2005, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2005, Bu çalışmada, kazıklara etkiyen düşey yük tiplerine, düşey yükler altındaki tek ve grup kazıkların davranış esaslarına ve düşey yüklü kazıkların analiz yöntemlerine değinilmiştir. Plaxis 3D Foundation Sonlu Elemanlar Programını kullanılarak tek ve perde kazıklar için üç boyutlu model ile analizler yapıldı. Analizlerde kullanılan çeşitli kazık çaplarında kazıklar arası ara mesafenin taşıma gücüne etkisi incelendi. Kazıklar, perde kazıkları olarak, eksenden eksene mesafeleri önce 3D, sonra 2D, daha sonra 1,5D ve D (teğet) olacak şekilde yerleştirilip, her bir ara mesafe için ayrı ayrı modellendi. Analizlerde zemin yapısı göçünceye kadar yükleme yapılarak, her kazık ara mesafesi için yük-oturma grafikleri elde edildi. Sonuçların değerlendirmesinde baz alınacak değer olması için, kazık çapı, kazık boyu ve zemin yapısı sabit tutularak ortamdaki tek kazığın düşey yük altındaki davranışı modellendi ve yük-oturma eğrisi elde edildi. Aynı kazık çapı için elde edilen yük-oturma eğrileri aynı grafik ekseninde çizilerek, kazıklar arası mesafenin taşıma gücüne etkisi belirli kriterlere göre değerlendirildi., In this study, pile load types, behavior of axially loaded piles and pile groups, analysis methods for axially loaded piles are mentioned. The effects of spacing between piles on bearing capacity are determined by using Plaxis 3D Foundation Finite Element Program. To investigate group interaction effects on bearing capacity as a function of pile spacing, full-scale 3D finite element models are performed on pile walls where the piles spaced at variable pile distances (like 3D, 2D and 1,5D) and also where the piles are tangent. In analysis, axial load is applied to the piles until soil body collapse. With the analysis, load – settlement graphs are obtained for variable pile spacing and pile diameter. Lastly, to find the base load – settlement graph for evaluation of the analysis results, the behavior of axially loaded single pile modeled and its load-settlement graph is obtained by taking pile diameter, pile length and soil profile constant. The effects of pile spacing on bearing capacity is determined by comparing the load-settlement graphs which was found for same pile diameter, according to some particular criteria’s., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2004, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2004, Deprem etkisinde kalan istinat duvarları, büyük ölçüde ek dinamik basınçlar nedeniyle zarar görmektedir. Depremli ve depremsiz durumda istinat duvarına etkiyen yükler farklıdır ve istinat duvarı etki eden tüm yüklere göre güvenlikle boyutlandırılmalıdır. Konsol istinat duvarları günümüzde hala en çok uygulama alanı bulan istinat duvarı türlerinden biridir ve diğer dayanma yapıları gibi dinamik kuvvetler etkisinde kaldıklarında göçme riski taşımaktadırlar. Bu Yüksek Lisans Tezi’nde, konsol istinat duvarlarının Türk Deprem Yönetmeliği’ne göre tasarımı ile ilgili daha önce yapılan bir çalışma incelenmiş ve bu çalışma geliştirilmiştir. İstinat duvarlarının deprem etkisindeki tasarımında bir çok parametre etkendir. Yapılan çalışma, Afet Bölgelerinde Yapılacak Yapılar Hakkında Yönetmelik’e göre konsol istinat duvarlarının tasarımı ile ilgili olup, farklı deprem bölgeleri ve değişen zemin özellikleri için konsol istinat duvarlarının tasarımında etkin olan, depremli vaya depremsiz durumların ve elverişsiz stabilite tahkiklerinin belirlenmesi ile seçilebilecek minimum duvar genişliğinin belirlenen parametreler dahilinde incelenmesi üzerine yoğunlaşmaktadır. Bunun için, duvar yüksekliği, dolgu ve temel zemini özelliklerine ait değişkenler kullanılarak dört deprem bölgesinde depremli ve depremsiz durum için çözüm yapılmış, stabilite tahkikleri incelenmiştir. Yapılan parametrik çalışmanın sonucunda, 4 farklı deprem bölgesi için minimum duvar genişliğinin duvar yüksekliğine oranı olan B/H değerleri ile dolgu zemininin içsel sürtünme açısı; ’nin değişim eğrileri elde edilmiştir. Elde edilen eğriler konsol istinat duvarlarının ön boyutlandırılmasında kullanılabilecek niteliktedir., Retaining structures are mostly damaged by the dynamic pressures occurring due to the soil conditions under earthquake loading. Retaining walls are designed to resist the loads both in seismic and static conditions by safety factors. Cantilever retaining walls are one of the most frequently used retaining structures and are susceptible to failure during strong earthquakes like the other retaining structures. In content of this study, a former study on cantilever retaining wall design under earthquake conditions according to Turkish Design Code, is discussed and a further model study of a cantilever wall to improve the former approach is proposed. There are many parameters that are affecting the design of retaining walls. This study is related with the design of cantilever retaining walls according to the Turkish Design Code. In different seismic zones with changing soil parameters, critical stability checks in seismic or static conditions are investigated. Besides, the change of the minimum wall width-satisfying the safety factors-with the variables are investigated. For this reason; concerning the variables of wall height, properties of backfill material and foundation soil, walls are designed in four different seismic zones with minimum base width and critical stability checks are determined. As a result of this parametric study, angle of friction of the backfill material: versus B/H-ratio of minimum base width to height- curves, for four different seismic zones are given. The curves that are obtained can be used in the design of cantilever retaining walls., Yüksek Lisans, M.Sc.

BUHAR TÜRBİNLİ ELEKTRİK ENERJİSİ JENERATÖR TEMELİ TASARIMI ÖZET `Buhar türbinli elektrik enerjisi jeneratör temeli tasarımı` konulu bu çalışmada, kurulu gücü 12.4 MW olan ve yıllık ortalama olarak yaklaşık 105 GWh enerji üreten bir kojenerasyon ünitesinde bulunan Turbo-jeneratör grubunun rezonans bölgesi civarındaki frekanslarda ve çalışma frekansındaki davranışı incelenmiştir. Çalışmada klasik analiz yöntemlerinden farklı olarak iki tabakalı zemin ortamında yüzeyde oturan makina temeli, 3-Boyutlu olarak modellenip makina-temel-zemin etkileşimini de göz önünde bulundurarak analizler yapılmıştır. ^EJaştjfcplastik zemin parametreleri tanımlaması yapılıp, makinada bulunan dönen parçalarının oluşturduğu merkezkaç kuvvetler sebebiyle oluşan dinamik etkinin sadece düşey bileşeni dikkate alınarak yapılan analizler sonucu elde edilen genliklerin makina üreticisi tarafından konulan sınırlar içinde olup olmadığı kontrol edilmiştir. Yeraltı suyu etkisi dikkate alınmaksızın yapılan analizler neticesinde temel sisteminin düşey titreşim genlikleri açısından yeterli olduğu görülmüştür. Ancak maksimum deplasman genliği beklendiği gibi rezonans frekansında değil de, çalışma frekansında meydana gelmiştir. Birinci bölümde çalışma ile ilgili geliştirilmiş analiz yöntemlerinden bahsedilip çalışmanın amacı ve kapsamı hakkında bilgiler sunulmuştur. İkinci bölümde makine ve temel tiplerinden kısaca bahsedilip yüksek hızlı makinalara ait temellerin tasarım esasları hakkında genel bilgi sunulmuştur. Üçüncü bölümde titreşim teorisi ve makina temellerinin tasarımında göz önünde bulundurulması gereken titreşim ölçütleri özetlenmiştir. Dördüncü bölümde zeminlerin dinamik davranışı ve dinamik zemin parametrelerinin belirlemesinde kullanılan deney yöntemleri verilmiştir. Beşinci bölümde analizler sırasında kullanılan sonlu elemanlar programı hakkında genel bilgi verilmiştir. Altıncı bölümde sonlu elemanlar modelinin geometrik özellikleri yanında çalışmaya konu olan makinaya ait makina üreticisi tarafından verilen tasarım karakteristikleri, tesisin bulunduğu yerdeki zemin şartları ve kullanılan zemin davranış modeli açıklanmıştır. Son bölüm olan yedinci bölümde analizlerden elde edilen sonuçların değerlendirilmesi yapılarak ileri çalışmalar için öneriler sunulmuştur. DESIGN OF A STEAM POWERED TURBO-GENERATOR FOUNDATION SUMMARY In this thesis entitled `Design of a Steam-Powered Turbo-Generator Foundation`, the behavior of a turbo-generator plant of 12.4 MW nominal power, producing, on the average, about 105 GWh of energy per year, was investigated around the resonant and working frequencies. In the present study, apart from classical analysis methods, analyses were performed taking into account the soil-foundation- machine interaction using a 3-dimensional model with a block foundation resting on the surface of a two layered soil medium. In the modeling phase, elasto-plastic soil parameters were defined and assigned to the soil elements and only the vertical component of the centrifugal forces caused by the operation of machine was taken into account. The displacement amplitudes obtained from the analyses were compared with the limits specified by the manufacturer. The results of analyses that performed without considering effect of underground water showed that the foundation system is sufficient for the vertical vibration amplitudes. However, the maximum displacement amplitude occurred, as estimated not at the resonance frequency but the operating frequency. In the first chapter some information on analysis methods reported in the related literature are cited, and then the objective and scope of the study are defined. In the second chapter, following a brief presentation of information on the types of machines and the foundations, general information on design criteria about high speed machine foundations are presented. In the third chapter, vibration theory and the design criteria to be taken into account for machine foundations are given. The fourth chapter contains information on dynamic soil behavior and experimental methods for determining the dynamic soil parameters. In the fifth chapter, general information about the finite element program used for performing the analyses is given. The sixth chapter contains information about geometrical properties of finite element model used as well as design characteristics proposed by the vendor of machine and soil conditions where the plant is installed. In the concluding chapter, interpretations of the analyses results and proposals for future studies are presented. 91

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2001, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2001, Bu çalışmada, yatay yüklü tek ve grup kazıklarının sonlu elemanlar yöntemiyle nonlineer analizleri yapılmıştır. İki grup analiz yapılmıştır. Birincisinde, model deneyi ve sonlu elemanlar programıyla yapılan bir çalışma Lusas ile analizleri yapılarak sonuçları karşılaştırılmıştır. Bu analizlerde hem tek kazık hem de 3x3’lük kazık grubu modellenmiştir. Sonuçlar arasında iyi bir uyum olduğu gözlenmiştir. İkinci grup analizlerde farklı kazık başlığı çevre ortamı, kazık çapı ve kazık boyu kullanılarak, tek ve 2x2’lik grup kazıklarının davranışı incelenmiştir. Problemin gerçekçi modelinin kurulabilmesi için elasto-plastik zemin davranışı ve kazık-zemin-kazı etkileşimi göz önüne alınmıştır. Ara yüzey elemanları kullanılarak kazık zemin ara yüzeyinde kaymalar tariflenmiştir. Kazık ve başlık arkasında ara bağlantı elemanları kullanılarak zemin elemanlarında çekme gerilmesinin oluşması engellenmiştir. Sonuçları literatürdeki çalışmalarla karşılaştırdığımızda sonlu elemanlar yöntemi ile önerilen yöntemler arasında iyi bir ilişki olduğu gözlenmiştir., In this study, nonlinear analysis of laterally loaded single and group piles are analyzed. Two group of analyses are done. In the first, a study which model tests and finite element program results are present, is analyzed with Lusas and results are compared. In these analyses, both single pile and pile group that contains nine pile, is modelled. A good correlation between model test and the analyses is seen. In the second group of analyses, the behaviour of both single pile and pile group that contain four pile, is examined by using different pile cap surroundings, pile diameter and pile length. Elasto-plastic soil behaviour and pile-soil-pile interaction which represents a realistic model to simulate the problem, is considered in the Lusas analyses. By using interface elements slippage is described on the pile-soil interface. Joints elements are used behind the pile and cap to prevent the tension stresses in the soil. The comparison of the results with the examples given in the literature is in a good agreement., Yüksek Lisans, M.Sc.

ZEMİNE GOMULU BORULARIN SONLU ELEMANLAR YÖNTEMİ İLE İNCELENMESİ ÖZET Zemine gömülü boruların üzerine etkiyen toprak yüklerinin hesaplanmasında teorik hesaplar gerçek zemin ve imalat koşullarını yansıtamamakta olup, boruların tasarımı sırasında yanılgılara düşülebilmektedir. Günümüzde, nümerik hesap metotlanndaki gelişmelere paralel olarak, zemine gömülü boruların üzerindeki toprak yüklerinin hesaplarında sonlu elemanlar yöntemi kullanılmaya başlanmıştır. Sonlu elemanlar yöntemi boruların tasarımında çeşitli inşaat aşamaları, zemin yapısındaki farklı tabakalar ve plastik zemin davranışı gibi faktörlerin etkilerinin göz önüne alınabilmesi mümkün kılmaktadır. Sonlu elemanlar yöntemi, malzeme özelliklerinin çeşitliliğini ve sınır koşullarının farklılığım güçlükle karşılaşmadan bağdaştırabilen, kullanımı kolay çok yönlü analiz yöntemlerinden biridir. Bu yöntem inşaat ve geoteknik mühendisliğinde yükleme, gerilme-şekil değiştirme, akım, konsolidasyon, taşıma gücü, zemin dinamiği veya genel olarak dinamik davranış, malzeme çeşitliliği olan durumlarda kullanılmakta ve iyi sonuçlar vermektedir. Bu çalışma iki kısımdan oluşmaktadır, ilk kısımda zemine gömülü boruların yerleşim şartlan, boruya etkiyen yüklerin hesabı, zemin-boru rölatif rij itlikleri, boruların tasarımını etkileyen unsurlar genel olarak anlatıldı. İkinci kısımda sonlu elemanlar programı ile yapılan analizler ve bu analizlerden elde edilen sonuçlar değerlendirildi. Sonlu elemanlar yöntemi hakkında bilgi verildikten sonra Lusas programı kısaca anlatılıp, analizler sırasında kullanılan model açıklandı. Farklı zemin ortamları, geri dolgu yükseklikleri ve boru çaplan kullanılarak çeşitli analizler yapılıp, analizler sonucunda elde edilen değerler grafiklerle birlikte sunuldu. Analiz sonuçlanna göre yataklamanın, boru çapımn ve geri dolgu yüksekliğinin boru üzerine etkiyen gerilmelerdeki etkisi incelendi. THE ANALYSIS OF BURRIED PIPES WITH FINITE ELEMENT METHOD SUMMARY During the design stage of the buried pipes there may be errors due to the fact that the theoretical calculation of the ground loads which is exerted on the buried pipes does not reflect the real ground and manufacturing conditions. Nowadays, the finite element method has been started to use in the calculation of the loads on the buried pipes in parallel way to the developments of the numerical calculation methods. Finite element method in design of pipes enables to be taken into consideration of the different stages of the construction, different layers of the ground and the plastic ground behaviour. Finite element method is one of the analysis method which is easy to use and harmonises without any difficulty the various material properties and the numerous border conditions. This method enables to have reasonable results in civil and geotechnical engineering for calculation of the loads, stresses, strains, flow, consolidation, carrying (loading) capacity, ground and general dynamic analysis where there is different kinds of materials. This study has two sections. At the first section, the burying conditions, calculation of the loads on pipes, pipe-ground relative rigidity, the factors influences the design have been generally defined. At the second section, the analysis that has been done by the finite element method and the results of the above mentioned have been evaluated. After giving brief information about the finite element method, the Lusas program has been introduced and the model that is used in the analysis has been explained. The analysis results which have been done for different ground conditions, backfill heights and pipe diameters have been presented with the aid of graphics. The influences of pipe dimension, bedding and backfill on the buried pipes have been examined considering the analysis results. XI 109

YATAY YÜKLÜ KAZIKLARIN SONLU ELEMANLAR YÖNTEMİ İLE 3 BOYUTLU NONLİNEER ANALİZİ ÖZET Bu çalışmada kazıkların yatay yükler etkisi altındaki davranışları incelenmiştir. Çalışmayı iki kısma ayırmak mümkündür. Bunlardan birincisinde genel olarak kazıklardan bahsedildikten sonra yatay yüklü kazıklarla ilgili bilgilerin verildiği bölümler yer alır. Kazıklardan ve yerleştirilme şekillerinden bahsedildikten sonra yatay yüklerin zeminde oluşturduğu etkiler üzerinde durulmuş, kırılma bölgeleri incelenmiştir. Kazıkların tekil veya grup kazıklan olmaları hallerinde oluşan farklılıklar ele alınmıştır. Yatak katsayısı teorisi hakkında detaylı bilgiler verilmiş, bu teori kullanılarak geliştirilen hesap yöntemleri açıklanmıştır. Bunlara ek olarak elastik teori anlatılmıştır. Broms tararından geliştirilen yöntem ile p-y eğrileri üzerinde durulduktan sonra her iki hesap yönteminin farklı zeminlerdeki kullanım prosedürleri açıklanmıştır. Bunlara ek olarak son üç yıl içinde yatay yüklü kazıklar hakkında yapılan çalışmalardan ikisi tanıtılmıştır. Çalışmanın ikinci kısmı sonlu elemanlar programı ile yapılan analizler ve bu analizlerden elde edilen sonuçları esas alır. Sonlu elemanlar yöntemi hakkında bilgi verildikten sonra sonlu elemanlar programı kısaca anlatılmış, analizler sırasında kullanılan model açıklanmıştır. Bu modelde yer alan elemanlar ve malzemeler tanıtılmış, modelin seçilme nedeni üzerinde durulmuştur. Farklı zemin ve kazık özellikleri için yapılan analizler sonucunda elde edilen değerler grafiklerle birlikte sunulmuştur. Araştırmacıların bu konu üzerinde yapmış olduğu çalışmalardan elde ettikleri sonuçlara da yer verilmiştir. En son bölümde yapılan çalışma ile ilgili bir değerlendirme bulunmaktadır. XII 3 DIMENSIONAL NON-LINEAR ANALYSIS OF THE LATERALLY LOADED PILES WITH THE FINITE ELEMENT METHOD SUMMARY In this study the behaviour of piles under lateral loads is presented. The study is seperated in two parts. In the first part the piles are discussed generally then the analysis of laterally loaded piles are detailed. Before explaining the effects of lateral loads on soil and possible failure zones the piles are detailed according to their types and installation method. Then the differences between single and group piles are given. Detailed information about subgrade reaction approach and methods using this approach are presented. Elastic theory, method proposed by Broms, p-y curves proposed by Reese and friends are discussed with their procedures for different soil types. The second part of the study contains the analysis made with the finite element program and all of the results of these analysis. After the program explained the model used during the analysis detailed, the element type, material properties and etc. are explained. The results are shown according to pile diameter and pile length seperately for different soil types. The results obtained from the analysis for different soil and pile parameters are given together in the last section to have an idea about the general deformation charactericticsof the piles under lateral loads. xm 142

DERİN KAZILARDA ÇOK SIRA ANKRAJLI İKSA SİSTEMLERİNİN TASARIMI VE BİR BİR BİLGİSAYAR PROGRAMI İLE DESTEKLENMESİ ÖZET Büyük kentlerde nüfus yoğunluğunun beraberinde gelen trafik, konut açığı gibi sorunlara çözüm getirmek bakımından yeraltı tesislerini arttırmak ve daha az yer kaplayan yüksek yapılar inşaa etmek yoluna gidilmiştir. Derin kazı gerektiren bu tip yapıların inşaası boyunca dar olan kazı sahaları içinde kazının düşey olarak teşkilini sağlamak, kazı sahasının çevresinde bulunan bina, yol ve mevcut tesislerde oluşabilecek hasar riskini en aza indirmek ve kabul edilebilir sınırlar ölçüsünde tutmak için göçme, kayma ve deformasyona engel olacak destekleme sistemleri yapılmaktadır. Kazı derinliklerinin önemli derecede büyük olduğu metro, yüksek bina temeli gibi yapılarda payanda, istinat duvarı gibi klasik destekleme sistemlerinin kullanılması yeter derecede güvenli olmamakta ve gerek ekonomik bakımdan gerekse inşaat alanını daraltması bakımından tercih edilmemektedir.. Bu durumlarda, zemin mekaniği ve temel mühendisliği bilgileri kullanılarak fonksiyonel, emniyetli ve ekonomik iksa perdeleri inşa edilmektedir. Derin kazı çukurlarının güvenli ve ekonomik olarak desteklenmesi için çok sıra destekli iksa sistemleri geliştirilmiştir. Derin kazı destekleme sistemlerinin rijitlikleri istinat yapılarına göre daha azdır. Ek olarak, destekleme sistemlerinde, bölgesel toprak basıncı yığılması sonucu destekleme sistemlerinin elemanlarında çok büyük yükler oluşmakta ve bunun sonucunda da sistemin toptan göçmesine neden olabilecek bir ardışık göçme mekanizması meydana gelebilmektedir. Yapılacak kazı nedeniyle oluşacak yatay hareketler kabaca, parabolik olarak nitelendirilebilecek basınç dağılımının oluşmasına yol açar. Çok sıra ankrajlı destekleme sistemlerinin boyutlandınlmasında gerçek toprak basıncı değerleri kullanılamadığından bir çok araştırmacı tarafından çalışmalar yapılmış ve zemin cinsine göre farklı toprak basıncı dağılımları elde edilmiştir. Bölüm 2' de çok sıra destekli iksa sistemlerinin tasarımında kullanılıcak toprak basıncı dağılımları incelenmiştir. Zemin ankrajlan, payanda veya istinat duvarlarının yetersiz kaldığı veya ekonomik olmadığı durumlarda, derin kazıların güvenle açılması ve inşaat sırasında emniyetli olarak durması için, yüksek şev duvarlarının desteklenmesinde kullanılan son derece yaygın destek elemanlarıdır. Bölüm 3 'de ankrajlann tasarım esasları ve hesap yöntemleri çeşitli ülke standartları gözetilerek incelenmiştir. Destekleme sisteminin elemanları, sisteme etkiyen toprak basıncına göre boyutlandınhr. Destekleme sistemine gelen toprak basıncı, önemli oranda sistemin deformasyonuna bağlıdır. Rankine ve Coulomb tarafından geliştirilen toprak basıncı teorileri dayanma duvarlarına, zemine ankastre perde duvarlara, tek sıra yatay destekli veya ankrajlı zemine sabit mesnetli veya ankraste perde duvarlara uygulanabilmekle beraber çok sıra yatay destekli veya ankrajlı destekleme xisistemlerine uygulanamazlar. Bu, çok sıra destekli sistemin yapılış aşamalarının, deformasyon biçiminin ve sistemin göçme mekanizmasının diğerlerinden farklı olması ile açıklanabilir. Bölüm 4'de çok sıra ankrajlı iksa sistemlerinin tasarım esasları incelenmiş ve çeşitli destekleme sistemleri hakkında bilgiler verilmiştir. Bilgisayar programlama teknolojisi, bütün mühendislik alanlarında olduğu gibi geleceğin anahtar teknolojilerinden biridir. Bilgisayar programlarını üretmeden satın alıp kullanmak pratik gibi gözükse de, teknoloji üretimi sürecinden geçilmediği için, sistemi üretenler kadar verimli kullanma olasılığı yoktur. Ayrıca teknoloji üretiminde bulunmayanların yeni teknoloji geliştirme şansının daha az olduğu da açıktır.Bu nedenle geoteknik alanında teknoloji üretimine yönelik gerek bilgisayar yazılımı alanında, gerek yeni deney sistemlerinin geliştirilmesi alanında ve de gerekse yeni yapım yöntemlerinin geliştirilmesi alanındaki çalışmalar desteklenmelidir. Bu amaçla bu tez çalışması kapsamıda çok sıra ankrajlı iksa sistemleri ile ilgili bir bilgisayar programı Microsoft Vısual Basic Programlama dili ile geliştirilmiştir. MS Visual Basic çok amaçlı ve aynı zamanda kolaylıkla program geliştirilmesini sağlayan bir programlama ortamıdır. MS Visual Basic programlama diliyle geliştirilen programlannWindows işletim sistemi altında çalışması kullanıcıya veri girişi, analiz ve sonuçların kolay yorumlanabilmesi imkanım tanımaktadır. Geliştirilen program Bölüm 2, Bölüm 3 ve Bölüm 4'de verilen teori ve hesap yöntemlerine ve çeşitli ülkelerin konuyla ilgili standartlarına dayanarak geliştirilmiştir ve Bölüm 5'te geliştirilen program ayrıntılı olarak tanıtılmıştır. Geliştirilen program ile bir iksa sistemi projelendirilerek, elde edilen sonuçlar değerlendirilmiştir. xn ANALYSIS OF MULTIPLE ANCHORED EARTH - RETAINING STRUCTURES IN DEEP EXCAVATIONS AND PROGRAMING OF AN ANALYSIS SOFTWARE PACKAGE. SUMMARY During the last few decades, deep excavations are becoming an important investigated object in the field of Geotechnical Engineering. The decrease in available construction areas and environmental effects such as neighbouring buildings, roads and other structures, have played an important role in the development and the necessity for the application of deep excavations, especially in great settling centers. It has been observed that the use of classical retaining structures like retaining walls are not safe enough and also not economical solutions to projects requiring deep excavations. A spectrum of these projects include underground subway tunnel constructions, high rise buildings, and the retaining of high slopes. Under geotechnic and foundation engineering considerations, the design of more functional, safer and more economical solutions like multiple anchored earth retaining structures are introduced. A lot of earth retainig systems have been developed to solve problems encountered during deep excavations. The problems maybe classified as displacement of the gorund during and after excavation, stability problems of the earth, high levels of underground water, uplift of the ground on the excavation surfaces, loads caused by environmental effects such as near structures and roads, existing undergorund sturctures and dynamic loads i.e. vibration problems. In this research multiple anchored earth retaining structures in deep excavations are examined in detail. In any such study many assumptions have to be made, the validity of which, in some cases, may be doubtful. Consequently these analyses can only be considered as guides for design which might assist engineering judgement. The mechanics of anchored earth retaining structure's behaviour can not be divorced from excavation behaviour since one attracts the other. The digging of an excavation causes a three dimensional change in the stress in the ground and as a result ground movements occur. When an anchorage system is used to support an excavation retaining wall, the design assumption made is to balance the lateral pressures on the wall by the horizontal components of the anchor loads. Thus lateral earth pressure change caused by excavation works is balanced whilst vertical stress change is not. As a consequence of this, the shear stresses induced in the ground increase with excavation deepening, causing the ground and the wall support system to deform in a complex manner dependent on the flexibilty and yield capabilities of the wall, the anchors and the ground respectively. Many variables such as construction sequence Xlllcan not be dealt within a satisfactory manner analytically and consequently use has to be made of field trials and field observations to assess the significance of a particular construction sequence. The rigidity of earth retaining structures are less than the rigidity of classical retaining walls. Due to the horizontal movement of the earth during the excavation, it is expected to cause a parabolic load on the earth retaing structure. Classical approcahes like the Rankine and Coulomb theories are not valid in the design of multiple anchored earth retaining structures, hence certain amprical relations are developed and used in the design phase of the project. Many researches have provided these ampirical relations such as Terzaghi - Peck and Lehmann assumptions. A detailed study of these ampirical correlations are presented in Section 2 of the present work. Standarts of different countries are also presented in the same section, such as The Swedish Standarts for Anchorages SIA-191, and Swedish Building Code In recent years, new applications for ground achorage systems have to continued to appear regularly and today anchorages may be associated with earth retaining structures. There is a need for a detailed knowledge of the ground, which may demand a supplementary investigation and a proper design related to static and dynamic loads, location of anchorages, load transfer lengths and overall stability. Section 3 investigates the British Standart Code of Practice for Ground Anchorages BS-8081. The design considerations of multiple anchored earth retaining structures are presented in detail in Section 4 of the present work. A comparison of different types of earth retaining structures such as diaphram walls, reinforced concrete walls and pile walls is also available in the same section. Taking into consideration the rapid developments in computer technologies, the need for a computer program that is capable of analyzing multiple anchored earth retaining sturctures is evident. The idea of using presently available software, instead of producing such a software, may be thought of a common practice today. However, it is obvious that, without a contribution to technology, it is impossible to deal with rapidly growing countries and technologies. With these in mind the software was developed under Microsoft Visual Basic programing language for the analysis for multiple anchored earth retaining structures. The ease and ergonomicity of Windows operating system, makes it possible to input data, to process it and visualize the results easily and efficiently. The program is explained in detail, including the solution steps necessary, and the graphical user interface in Section 5. A sample case with the actual data from a recent project is analzed, and the results are presented in Appendix 1. The newly developed software package in the present work may be further developed to transfer data into CAD environments, for ease on project basis, and other solution modules that might be needed for possible future work can be added with ease. XIV 134

Zemin stabilizasyonu geoteknik mühendisliğinde ana bir başlık altında değerlendirilebilecek çok yönlü, uygulamalara açık bir konudur. Son 25 yıldır uygulanmakta olan pasif zemin armatürleri, zemin çivileri ise zemin stabilizasyonunu için kullanılan en yeni ve en geçerli tekniklerden biridir. Özellikle kolay ve tasarruflu imalatı, gösterdiği üstün performansı ile son yıllarda bir çok projede değerlendirilmiş, başarıyla uygulanmıştır. Zemine çivilenmiş yapıların tasarımına yönelik birçok güncel metod mevcuttur. Bunlar sırası ile Davis, Fransız, Alman Metod'ları ile Kinematik Limit Analiz ve Sonlu Elemanlar Analiz Yöntemleridir. Bu metodlardan ilk üçü limit denge prensibine dayanırken, son ikisi limit analiz yaklaşımını içerir. Metodlarda kayma yüzeyi bi-lineer, dairesel, parabolik veya log-spiral olarak kabul edilirler. Stabilite analizleri İle kayma yüzeyini kesen takviyelerin, limit kesme, çekme ve sıyrılma kapasiteleri araştırılır. Teknolojinin gelişmesi, beraberinde zaten kuvvetli işlem hacmi olan bilgisayarları daha da güçlendirmiş, mühendisliki çalışmalar için çok daha cazip kılmıştır. Bu süreci takiben bilgisayar destekli teknik yazılımlar oluşturulmuş ve kullanıma sunulmuştur. LUSAS sonlu elemanlar programı da bu amaca istinaden kullanıma sunulmuş çok amaçlı bir teknik yazılımdır. İçerdiği zengin malzeme ve geometrik özelliklerlerle desteklenmiş bünye denklemleri, çok yönlü ve çeşitli eleman kütüphanesi ile LUSAS konusunda oldukça iddialıdır. Bu tez çalışması ile amaç, zemin çivileme tekniğim tüm yönleriyle sunmak, tasarımına ait prensiplerin altım çizmek ve uygulamaya yönelik bilgileri değerlendirmektir. Ek olarak LUSAS 12 versiyonu kullanılarak zemin çivisi modellenmiş ve davranışı analiz edilmiştir. The determination of forces acting on structures which are connected to or in direct contact with earth mass is one of the paramounth importance in applied Geotecnical Engineering. Considering the increasing demand for deep excavations in connection with extenstive land utilisation within densely populated areas and as a result of increasing value of land, the ecenomy and construction speed of soil nailing has made the method an understanding alternative for both temporary and permanent excavations. Soil nailing has been used in a variety of civil engineering projects in the last three decades, mainly in Europe, to retain excavations and stabilize slopes. The earliest reported works were retaining wall construction in Spain, France and Germany, in connection with highway or railroad cut slope construction or temporary building excavation support. In North America the system was initialy used in Vancouver in the earliest seventies for temporary excavation support. The fundamental concept of soil nailing consists of placing in the ground passive inclusions, closely spaced, to restrain displacements and limit decomression during and after excavation. The nails are generally steel bars, metal tubes or other metal rods that are embedded in grout if necessary, to establish required safety factor against not only tensile forces but also shear stresses and bending moments. Stability of the slope face between nails generally is ensured by providing a thin layer of shotcrete reinforced with wiremesh. Nailing differs from tieback support systems in that the nails are passive elements that are not post tensioned as tiebacks are. Method has been used both granular and cohesive soils and relatively heterogeneous deposits. The principal function of nails in slopes and embankments is to provide stabilizing forces. Through friction between the nails and the soil, acting over a sufficient length, it is possible to develop enough resistance to pullout so that the full tensile strength of the reinforcement can be mobilized to help stabilize the slope. Modes of failure of nailed slopes and embankments include tensile failure of the reinforcement, pullout of the reinforcement from the soil, excessive deformation of the reinforcement and also raveling of the soil from between layers of reinforcements at the face of steep slopes. If the reinforcement fails in tension or deforms excessively, the same type of shear failure can take place as would occur without reinforcement.Steel reinforcement inclusions currently used in soil nailing process can be classified as driven nails, grouted nails, jet grouted nails and encapsulated corrosion protected nails. Driven nails are suitable for temporary construction and have been 22 mm to 32 mm steel bars or structural angles for greater driving rijidity. They are closely spaced at 2 to 4 nails per m2 creating a homogenous composite reinforced soil mass. The nails are driven using vibropercussion pneumatic or hydraulic hammers. This installation technique is rapid an economical, but is limited in the lenght of the nail installed by equipment considerations in which boulders and coarse gravel and weathered rock is absent. Grouted nails are suitable both temporary and permanent construction. They are placed in boreholes that are advanced by either core drilling, rotary drilling, percussion drilling, auger drilling or driven casing. Grouting is performed by gravity or under low pressure from the bottom of the drill hole. Spacing is typically wider, from 1.2 to 1.8 m on center. Drill hole diameter will vary from 10 cm to up to 30 cm when using augers. Jet grouting nails are composite inclusions made from a grouted soil with a central steel nail, installed simultaneously. They are used for temporary aplications and may be used for permanent aplications if the degree of required corrosion protection is low. Nails can be installed using vibropercussion driving at high frequencies (up to 70 hz) and extremely high grouting pressures (>2000 psi). The grout under this technique is injected through a small diameter longitudinal channel in the nail, under a pressure sufficiently high to cause hydraulic fracturing of the surrounding soil. Alternatively, significantly lower grouting pressures ( psi ) have been use in practice with a variety of nails including hallow bars which are used as the drill stem initially and then disconnected and left in the hole to serve as the structurel members. Jet grouting tecniques provide in addition, recompaction and improvement of the surrounding soil and can increase significantly in granuler soils the shear and pullout resistance of the soil. Encapsulated corrosion protected nails are used for permanent structures requaring a high degree of corrosion protection. Encapsulation can be achieved by inserting the nail in a plastic or steel tube and filling the annulus with grout, prior or during grouting the drill hole. The facing functions to ensure local ground stability between reinforcements, limit decompression immediately after excavation and protect the retained soil from surface erosion and weathering effects the type of facing controls the aesthetics of the structure as it is the only visible part of the completed work. Depending on the application welded wire mesh, shotcrete, precast concrete or cast in place concrete facings has been used.There are several methods currently avalible for the design of nailed structures such as the German Method, the Davis Method, the French Method, the Kinematic Limit Analysis and the Finite Element Analysis approaches. The first three methods are based on the limit equilibrium approach whereas the last two are based on the limit analysis method. The basic concept underlying the design of soil nailed structures relies on:. The transfer of tensile forces generated in the nails in an active zone to a resistant zone through friction mobilized at the soil-nail interface.. Passive resistance developed on the surface perpendicular to the direction of the soil-nail relative movement. The frictional interaction between the ground and the nails restrain ground movement during and after construction. The resisting tensile forces mobilized in the nails induce an apparent increase of normal stresses along potantial sliding surfaces (or rock joints) increasing the overall shear resistance of the native ground. Nails placed accross a potential slip surface can resist the shear and bending moment through the development of the passive resistance. The chief design concern is to ensure that the soil-nail interaction is effectively mobilized to restrain ground displacements and ensure structural stability with an apporiate factor of safety. The construction of a soil nailed mass results in a composite coherent mass similar to reinforced fill systems. The locus of the maximum tensile forces separates the nailed soil in two zones:. An active zone (or potential sliding soil or rock wedge), where lateral shear stersses are mobilized and resuts in an increase of tension force in the nail.. A resistant (or stable) zone where the generated nail forces are transferred into the ground. The soil-nail interaction is mobilized during construction and displacements occur as the resisting forces are progresively mobilized in the nails. There are several methods currently avalible for the design of nailed soil structures such as, the German Method, the Davis Method, the French Method, the Kinematic Limit Analysis and the Finite Element Analysis aproaches. The first three methods are based on limit equlibrium method aproach, where as the last two are based on limit analysis aproach. These methods assume the failure surface to be bi linear, circular, parabolic or log-spiral. The variable limit shearing, tensile, and pullout resistances of the reinforcements crossing the failure surface are considered in the stability analysis. The identified design paraneters of a soil nailed system for all methods include, the mechenical or strength properties of the soil and inclusions, as well asparameters characterising the different mechanisms of soil-reinforcement interaction. They can can be classified in the following groups:. Mechanical properties of the insitu soil, particularly soil type, internal friction angle and cohesion...... Mechanical properties of the reinforcements, specifically the tensile and shearing resistances and the bending stiffness. Parameters related to the soil-reinforcement interaction by friction, particularly the limiting unit ultimate friction, Fi, which can be mobilized along the inclusion in the specific soil under consideration. Parameters related to the normal soil-reinforcement interaction by lateral earth thrust on the reinforcement, particularly the limit passive pressure of the soil and the modulus of lateral or subgrade reaction. Geometric properties of the reinforcements such as thichness, shape, length and of the structure such as vertical and horizontal spacings between the reinforcements; inclination of the reinforcements and of the facing. Parameters related to proposed installation method of the reinforcements, type of facing, grouting methods.. External load systems including surcharges, enviromental loading, embankment slopes, water flow and seepage forces. The design of soil nailed retaining structures is based on evaluation of:. Graund stability of the structure and the surrounding ground with respect to a rotational or translational failure along poteantial sliding surfaces.. Local stability at each level of nails Global stability analyses for retaining structures ocnsist of evalualating a global stability factor of the soil nailed retaining structure and the surrounding ground with respect to a rotational or translational failure along potantial sliding surfaces. It requires determination of the critical sliding surface which may be dictated by the stratification of the subsurface soil or in rock by an existing system of joints and discontinuties or position and intensity of surcharge loads. The potantial surface can be located inside or outside the soil nailed retaining structure. Analysis methods which provide a global safety factor, do not provide direct means of estimating working or failure nail tensile forces or provide criteria related to allowable displacements of the structure under working stress conditions. The availability of computers and of finite elment analysis computer programs, has made it possible to perform rational analyses of stress anddeformations in slopes and embankments. These analyses are capable of modelling several important aspects of actual conditions, including nonlinear stress-strain behavior, sequential changes in geometry during construction, and dissipation of excess pore pressures following construction. The finite element method has been used by several investigetors to analyze the behavior soil nailed retaining structures. These analyses involve different constitutive equations for the soil and interface elements to simulate soil-facing and soil-inclusions interaction. Comparisons of finite element predictions with observed behavior instrumented structures have been succesfull in indicating trends in parametric studies. However the use of finite element method in design is currently limited by the relatively high costs and raises significant difficulties with regard to:. The actual construction stages and installation process of the nails are difficult, if not pratically impossible, to simulate.. The complex soil-inclusion and soil-wall interaction is difficult to model. Several interface models have been developed but their implementation in design requires relevant interface properties which are difficult to properly determine.. Various elosto-plastic soil models can be used to predict soil behavior during exavation. However, determination of soil model parameters generally requires spesific an eloborate testing procedures limiting the practical use of these models. The finite element method has therefore been used mainly as a research tool to eveluate the effect of the main design paremeters on the behavior of the structure, ground movement, and working forces in the nails. This manual is proposed as a study of an extent analyse due to the behaviour of nailed soil structures with the LUSAS Finite Element System. 189

ÖZET Kazıklar ve kazıklı temeller, inşaat mühendisliğinde çok önemli bir yere sahiptir. Sorunlu ve taşıma gücü düşük olan zeminlere inşa edilecek binalarda, köprülerde, dolgularda, deniz yapılarında, şevlerin stabilitesinin sağlanmasında, otoyollarda, kazıların geçici veya kakçı olarak desteklenmesinde kazık veya kazıkların grup olarak değişik sekililerde ve amaçlarda kullanıldığını görmekteyiz. Geoteknik bir problemin çözümünün bir takım zorluklan vardır. Bunların başında zeminin üçfazlı ortam oluşu, homojen olmayışı ve elasto-plastik davranış göstermesidir. Bu özellikler zemini, diğer yapı elemanlarından ayırır. Zeminin malzeme özelliklerini iyi bir şekilde belirlemek ve bu özelliklerin yatay ve düşey mesafelerle değişimini gözlemek önemlidir. Zemin elasto-plastik bir malzeme olduğu için akma noktasını belirlemek önem kazanmaktadır. Çünkü bu noktadan sonra zemin taşana gücünün büyük bir bölümünü kaybetmekte, akıcı bir kıvam almakta ve büyük deformasyomar yapmaktadır. Kazık davranışı incelenirken, kazığın geçmiş olduğu tabakaların özelliklerim iyi bir şekilde belirlemek ve kazığın imalatı sırasında ki lokal özellik değişimlerini ve ekstra kuvvetleri göz önünde bulundurmak, kazık taşıma gücünü gerçeğe uygun olarak hesaplamamızı sağlayacaktır. Düşey yük altındaki bir kazığın taşıma gücü, kazığın taşıma gücünü etkileyen faktörlerden negatif çevre sürtünmesi ve yoğrulma etkisi Sonlu elemanlar programı LUSAS 11.3 kullanılarak yapılmıştır. Sonlu elamanlar programı, kullanıcıya çok değişik malzeme özellikleri ve yük durumları tanımlama kolaylığı sağlamaktadır. Lusas ile yapılan analizlerde, değişik çaplar da kazıklar kullanılmıştır. IX Piles one columnar elements in a foundation which have the function of transferring load from the superstructure through weak compressible strata or through water, onto stiffer or more compact and less compresible soils onto rock. They may be required to- carry uplift loads- when used to support taü structures- subjected, to overturning forces from winds or waves. Piles used in marine structures are subjected to lateral loads- from the impact of berthing ships and from waves. Combination of vertical or horizantal loads are carried where piles are used to support retaining walls, bridge piers and abutments and machinery foundations. The driving of bearing piles to support structures is one of the earliest examples of art and science of the civil engineer. In Britain the are numerous example of timber piling in bridge works and river side settlements constructed by the Romans, la Ghin% timber piling was-used by bridge builders of the han Dynasty ( 200-BC to AD 200) Timber, because of its strength- combined with- lightness, durability and ease, of cutting and handling, remained the only material used for piling until comparatively recent times. It was-replaced by concrete and steU only because these newer materials could be fabricated into units that were capable of sustaining compresive, bending and tensile forces far beyond the capacity of a timber pile of like dimension. Reinforced concrete, which was developed as a structural medium in the late nmeteenthr and early twentieth centuries, largely replaced timber for high-capaqity piling for works on land. It could be precast in various structural forms to suit the imposed loading and ground conditions and its durability was satisfactory for most soil and immersion conditions. Steel has- been used to on increasing extent for piling due to its ease of fabrication and handling and its ability to withstand hard driving problems of corrosion in marine structure have beer* overcome by the introduction- of durable coating and cathodic protection. While materials for piles can be precisely specified and their fabricationr and can. be controlled to confirm to strict specification and code of practice requirements, the conclusion of their load-carrying capacity is a complex matter which at the present time is based partly on theorical concepts derived from the science of soil and rock mechanics, but mainly on emprical methods based on experience. The conditions which govern the supportting capacity of the piled foundation are quite different. No matter whether the pile is installed by driving withr a hammer,by jetting by vibration, by jacking, screwing or drilling, the soil in, contact with the pile face, from which the pile derives its support by skin friction, and its resistance to lateral loads, is completely distrubed by the method-of installation. Similarly the soi} or rock beneath the toe of pile is compressed ( or sometime loosened ) to an extent which may affect significantly its- end, bearing resistance. Changes take place in tiie conditions at the pile- soil interface over periods of days, months or year which in turn depend on tiie relative pile-to sou movement, and chemical: or electio-chemieal effects caused by the hardening of concrete or the corrosion of the steel in contact with the soil where piles are installed- in groups to- carry heavy foundation loads, the operation of driving or drilling for adjacent piles can cause changes in the carriying capacity and load-settlement characteristic of the piles in the group-that have already been driven,. The soil parametres for static ( and group ) capacity analysis consist in the angle of internal friction ^ and the cohesion c. Controversy arises since some designers use undrained ( or total) stress where others-particulary more recently-use effective stress values^ The engineer is often presented with inadequate information, on the soil properties. He then has to decide whether to base his designs on conservative values with an-appropriate safety factor without any check by loads-testing or merely to use the design methods to give a preliminary guide to pile diameter and length and then to base the final: design on an extensive fields testing programme with- loading tests to failure. Such testing is always justified an a large-scale piling project. Proof- load testing asa means of cheeking- workmanship^ is a separete consideration. Where the effective overburden pressure is an important parameter for calculating the ultimate bearing capacity of piles ( as in the case for granular so£s ) account must be taken of the effects of a rise ground water levels. This may be local or may be general rise, due for example to^ seasonable flooding of a major river, ojj- a long term effect such as the predicted large general rise in ground water levels in Greater London. Piles driven into the mass always produce same to a very considerable remolding of the soil in the immediate vicinity of pile ( say, three to five pile diameters ) at this instant, undrained sou- strength parameters are produced, which- may approach remailed drained values if the degree of saturation is low. In general, however, there is some considerable time lapse ( several months to years) before full design loads are applied. In this interval the excess pore pressures dissipate and drained, remolded, soil parameters best decribe the soil behaviour. The pile capacity for soft clays increases with time, with most strength ramain oceuring in from 1 to 3 months This is-somewhat explained by the high pore pressures and the displaced volume effect producing a rapid drainage and consoliation ofthe sou very near the pile. In fact the soil very near the pile ( a zone of perhaps 50 to 200 mm ) tends to consolidate to such a high value that effective diameters of the pile is increased 5 to 7 percent over actual value. The reduced water content resulting from consolidation in this zone has been observed for some time. The increase is likely to be marginal in very stiff and/or overconsohdated clays; in fact the capacity may decrease slightly with time as the high lateral pressure dissipates via creep over a period of time. xtWhere piles are placed in predrilled holes, the existing soil state remains at wearly the drained conditions. Possible deterioration of the cohesion at the interface of the wet concrete and soil may occur but this may be partially offsett by the slight increase in pile diameter as grains in- the surrounding sou become part of the pile shat as-the cement hydrates. The loss of Ko from expansion into the cavity may be partially offset by the lateral pressure developed- from the wet concrete which has a higher density than the soil. Safety factors which commonly range from 2.& to 4,0 or more, depending on designer uncertaineties. In general, the safety factors are larger than for spread foundations because of the greater uncertainties in pile-soil interaction and-the fact the foundation is likely to be more expensive when piles are used. While equations are certainly not highly complex ia form,their suecesful use, to make a prediction of capacity which closely compares with a load test if often a fortunate event. This- is because of the difficulties in- determining the in situ- soil properties and which because in the vicinity of the pile after it is installed- driven or othervise. AdditionaHy,the sou, varibihry, both laterally, and- vertically, coupled with a complex pile-soil interaction creates a formidable problem for suecesful analysis. The-ultimate pile capacity Qu is not the sum of the ultimate skin resistance plus the ultimate point resistance. Ultimate skin resistance is produced at some small value of relative slip-between, pile and sou-, where slip between pile and sou, where is defined as the accumulated differences in shaft strain from axial load and soil strain caused by the-load trasfered to it via, skin resistance. This-süp-progresses down-the pile shaft with increased load. Where limiting shear ressitance is developed at large slips in the upper zoneSj part of tike load is transferred back kt©^ the pile shaft which ia turn- produces larger relative slips and at progressively greater depths. A study of load-settlement and load-trasfer curves from- a number of load-tests indicates that slip to developed maximum skin resistance is on the order 5 to 10 mm and is relatively independent of shaft diameter and embedment length, but may depend upon soil parameters. Mobilization of the ultimate point resistance requires a point displacement on tiae order of 10 percent of the tip diameter for driven piles-and up to 30 percent of the base diameter for bored piles and caissons. This is a total point displacement and in material other than rock may include point displacement caused by skin resistance stress transferred through the soil to produce settlement of the soil beneath the point. It is highly probable that in- usual range of working loads, skin resistance is the principal load-carrying mechanism in all but the softest soil. Since the pile unloads to the surrounding sou via resistance, the pile load will decrease from the top the point. The elastic shorthening ( end relative slip ) will be larger in the upper shaft length from the larger axial load being comied. Examination in the literature shows that the load transfer is approximately parabolic and decreasing with depth for cohosive soils. The load transfer, however, be nearly linear for cohesionless soils and the shape somewhat dependent on embedment depth in all materials. Generally a short pile will display a more linear load-trasfer curve a long pile ; however, this is somewhat speculative since not many very long have been instrumented for obvious reasons. sitGenerally, there will be a minimum of two or three piles under a foundation elemets- of footing to allow for nusaugnments-and other inadvertent eccentricities, T,he superimposed pressure intensity will depend on both pile load and spicing and if sufficiently large sour wiH fait in shear or the settlement wiH be excessive. The stress intensity from overlapping stressed zones will obviously decrease with increased pile spacing, s; however, large spacing are often-impractial since a pile cap-is-east over the pile group for the column base and/or to spread the load to the several piles in the group. The- soil stresses- on underlying strata- produced by the several piles- in- a- group are often required to make astrength or settlement estimate. These stresses are difficult to estimate for several reasons: 1. Infiuanee of pile cap-usually in direct contact with ground except on expansive soils. The results in both the contact soil and the pile carrying the load with the interaction highly intermediate. 2. The distribution of friction effects along the püe, which are generally not known ; hence point load is also not known. 3-. The overlap of stress fromadjacent püe% which is- difficult to evaluate. 4. The infiuanee of driving the piles on the adjacent soil. 5. Time-dependent effects such as- consolidations, thjxotrophy, varying loads, and change in groundwater level. Considering all these variables, it is common practice to simplify the stress computations in a few way. These analysises are to necessary to avoid overstressing the underlying deposits or consolidation settlements in clay deposit. As can be seen a pile group either transmits the load throughout a soil mass of depth Lf for friction piles or to-depth L for on end-bearing pie. The sou at or below these dephts-musfr carry the load without excessive deformation or the load must be transmitted to deeper strata. An analtieat method of evaluating the stresses in the strata undelying a- pile group uses authers extension of a method proposed by the Geddes adaption of the Mindlin soluation of a point load at tha- interior of an- elastic solid. As with- tiie Boussiness analysis, this method assumes the soil is semi-infinitive isotropic, homogenous and elastic. Sou does usually fit those assumptions; thus the soluations are in error, but they be as good as the Boussinesq soluation which is widely for footing- setiements. Geddes later made soluations for the Boussinsq case for subsurface loadings. These are generally less accurate than the Mindlin soluation. Poulos and Davis also used the Mindlin soluation to predict settlements^ Instead of presenting tables of stress coefficienct, they presented charts for settlement-influence factors. Either the Geddes or the Poulos and Davis solutions should provide the same deflection if properly used, since one can easily compute deflections from stresses, but stresses are not as easily back-computed from deflections, stresses may be needed for consolidation settlements. Analysis of the single pile bearing capacitys, shaft resistance, tip resistance, negative skin friction and remolding effects on the pile bearing capacity, load- xiiidisplecament, stress-strain curves and the relations between them were made with the LUSAS Finite Element System. Results of these analysis are given in a comparative way. JQV 171

ÖZET Zemin mekaniği, inşaat mühendisliğinin en yeni bilim dallarından biri olması özelliği ile ayrı bir öneme sahiptir. Kısa geçmişine karşılık çok yoğun bilimsel çalışmaların yapıldığı zemin mekaniğinin en yeni konularından birini de Donatılı Zemin konusu teşkil etmektedir. Pratik uygulamalarını çok eski dönemlerde (M.Ö 2500 yıllarında Ziggurat adı verilen tapınakların yapımında) görebileceğimiz bu konu, gerçek anlamda ilk kez 1963 yılında bir Fransız mimar-mühendis olan Henri Vidal tarafından bilimsel bir önem kazanmıştır. İlk proje uygulamalarını 1967 yılında gördüğümüz Donatılı Zemin konusu özellikle A.B.D, Fransa, Kanada ve Japonya gibi ülkelerde gelişme ortamı bulmuş, bu konuda çok sayıda uygulama projesi de gerçekleştirilmiştir. Bugün dünyanın pek çok ülkesinde olduğu gibi ülkemizde de donatılı zemin konusu gittikçe daha fazla dikkat çekmektedir. Bununla birlikte çalışma mekanizması anlaşıldıkça ve ekonomik olması özelliğinin farkına varıldıkça, daha geniş araştırma ve uygulama alanları bulacağım söylemek bir kehanet olmayacaktır. Bu çalışmadaki amaç ; taşıyıcı bir sistem olarak donatılı zemin konusunun irdelenmesi, zemin ve donatı elemanlarının oluşturduğu kompozit sistemin davranış mekanizmasının ilk ve en son yapılan çalışmalar ışığında gerek deneysel ve gerekse analitik metodlarla incelenmesi ve yorumlanmasıdır.. Bu incelemede yüzeysel temellerin taşıma güçlerinin donatı elemanları kullanılarak arttırılması konusu, sonlu elemanlar metodu ile nonlineer analiz yapan bir bilgisayar programı (Lusas 11.0) kullanılarak araştırılmış ve programın çalışma düzeneği hakkında da kısa bilgiler verilmiştir. XV11 SUMMARF SYSTEM BEHAVIOUR PROPERTIES OF REINFORCED EARTH STRUCTURES As a definition, reinforced earth is a composite structure of which sliding resistance has been increased, obtained by inserting metalic or polymer elements into earth in parallel direction to principal traction unit deformations for the purpose of increasing resistance and strength of earth in critical directions. Elements used as reinforcement can be metalic or polymer elements. In case that reinforcement elements are metalic, then, it should be necessary to inspect its non-corrosive mechanism. On the other hand, in case that reinforcement elements are polymer elements, hydraulic negative effect of water on reinforcement elements becomes very important. Molecular weights, and crystallisation rates, loading velocity and heat effect in behaviour mechanism of polymers play very significant role. Polymer reinforcement elements are called, in short, as geosynthetics. It is very important measuring properties of geosynthetics from engineering viewpoint. Properties such as weight per unit surface or length, thickness, rigidity, traction resistance (tensile strength) deformation properties, elasticity modules, seam residence, impact strength, penetration resistance, hydraulic permeability, resistance against chemical substances, friction properties, play great and important role in comprehension and interpretation of behaviour mechanism. In reinforced earth, reinforcement elements are inserted into earth mainly for purposes of carrying, separation, filtration and drainage. On the other hand, used filling materials must be selected by taking into consideration long term stability of construction, short term stability after construction and physical and chemical properties of filling material. Total longitudinal thrust-off will increase depending on how small is internal friction angle in filling material. The reason for this is that apparent friction XV1Ucoefficient is in direct proportion with internal friction angle of earth. Lateral tensions and deformations in reinforced earths are limited by reinforcement elements placed in parallel to 03 direction and hence, while deviathoric tension where potentially composite earth is broken, increases and in parallel to this, sliding resistance raises as well. This phenomenon is explained by two different theories. One of these theories is pseudo-cohesion theory. In accordance with this subject theory as long as angle made by strength between earth dunes and reinforcement with normal angle of reinforcement remains smaller than friction angle between earth and reinforcement. Then earth dunes will act as they are attached to each other. This attachment is called either apparent cohesion or pseudo-cohesion. Other theory is named Increased Ambience Pressure Theory. In accordance with this theory, strength increase in reinforced earths is not effected by apparent cohesion, but is realised by increase in lateral tension. When behaviour of reinforced earth retaining structures is examined, it is observed and seen that maximum sliding tension occurred on each reinforcement element, occurs at different points and by joining these points, then, two different zones emerge inside earth masses behind wall. One of zone is a region being neighbour to wall surface and called as active zone and sliding tensions in this zone is towards the wall. Other zone is a passive or resisting zone where sliding tensions are directed towards opposite direction of wall. Capability of reinforcement and earth in these structures is a function of unevenness of reinforcement surface unit weight of filling material, height of filling materials on reinforcement, internal friction angle of filling materials. As per results obtained on model studies conducted in laboratory on reinforced earth specimens, while reinforcement rate increases, so, internal friction angle of composite earth increases as well to certain point and after this point, remains fixed or decreases. Similarly, together with reinforcement rate, sliding resistance increases, but compaction quantity decreases. In addition, by increase of reinforcement rate, it is seen that elastoplastic deformations increase. Other laboratory studies have given the result that by increasing of slimness of reinforcement, bearing capacity has increased as well. XIXIt is possible to summarise other test results conducted in laboratory as shown below : 1. While reinforcement surface rate increases, CBR and secant modules increase as well. 2. While reinforcement is 4%, CBR has become five times greater than reinforcement specimens. 3. While reinforcement rate increases, a larger deformation in volume is formed for the same lateral deformation 4. If it is defined as K=a3/öı, increase of K value will decrease limited lateral deformations. 5. By increase of K value, deviathoric tension value decreases for the same axial deformation. 6. By increase of K value, pore water pressure decreases for the same axial deformation 7. Since pore water pressure is so small in tests with drainage, deviathoric tension comes out big. 8. It is suitable to use reinforcement in type having high hydraulic permeability in earth with cohesion and water saturated. As tests are conducted under laboratory condition on reinforced earth, full scale tests are performed in the field too. In these tests especially longitudinal earth tensions, vertical earth tensions and longitudinal and vertical earth deformations and longitudinal tension and deformations in reinforcement are determined and then determination of longitudinal thrust size transferred to wall surface of maximum reinforcement traction strength and vertical tensions formed throughout reinforcement as well as real field values are achieved one to one. Studies and examination conducted put forth that it is a for away possibility that a flow incident will occur in reinforcement and that reinforcement can be loaded only by a tension up to 11% of flow tension. On the other hand earth and reinforcement deformations exhibit a reverse form with each other towards inside from wall surface. xxIn studies, about finite elements conducted on matter of properties of filling behind wall used in reinforced earth resistance structures, three fillings behind wall have been tested. First of these fillings is cohesion filling, second one granular filling without cohesion filling and third one a mixed filling being granular in front and with cohesion behind. In conclusion of study, in case application of a mixed filling, both longitudinal and vertical deformations have decreased to a great extent. Idea in respect with increasing bearing capacity by application of reinforcement elements under surface foundation has become a topic of study during recent years. Both laboratory and finite element studies have put forth effective parameters on the subject-matter and through these studies, some significant results regarding increasing bearing capacity have been obtained. It has been determined that increasing bearing capacity of earths under surface foundations by reinforcement elements depends on five parameters and these parameters are respectively distance of first reinforcement layer to foundation base, distances between reinforcement, number of reinforcement layers, lengths of reinforcement and elasticity properties of reinforcement material. When soft earths under foundation are reinforced by compact sand and reinforcement elements, then bearing capacity increases and deformations are reduced. Conclusions obtained from studies with finite element and also laboratory studies can be summarised as follows : 1. Bearing capacity of soft earth under foundation is a function of proportion of sand filling thickness made for improvement purpose to foundation width. 2. Taking this proportion as 0,5 gives effective result. 3. Besides their reinforcement duty, reinforcement elements function as separator and will provide positive contribution from this viewpoint to carry power. 4. Friction resistance of geognd type reinforcement elements is higher as compared with others. 5. Both FEA and test studies have shown that optimum depth makes single layer BCR proportion to maximum level. This XXIdepth is around 30% of foundation width being independent to reinforcement dimensions. 6. In case that sitting proportion is bigger than 6%, this rank becomes higher than 30%. 7. It has been determined that maximum BCR value comes out if first reinforcement depth is taken as 25% of foundation with in case of multi-layer reinforcement. 8. Optimum reinforcement element space interval giving maximum BCR value is in rank of 20% of foundation width. 9. Number of optimum reinforcement layers varies between one and five and is effective in depth up to 1.5 times of foundation width. 10. While elasticity of reinforcement increases then BCR value increases as well. 11. Results of studies, about LUSAS finite element conducted by KESİM on subject of increasing bearing capacity of sand earth, supports above stated other results. XXH 206

ÖZET Günümüzde, nüfusun,sanayileşmenin ve ulaşımın artmasıyla birlikte yeni yapılanma bölgelerine ihtiyaç artmıştır. Bu ihtiyaç nedeniyle şehirlerde ve çevrelerinde önceden yapı yapılmaktan kaçınılan zayıf zemin özellikli yerlere yönelinmiştir. Bu bölgelerde planlanan yapılar içinde uygun temel çeşitlerinden biride KAZIKLI TEMELLER'dir. Kazıkların diğer temel çeşitlerine göre hem daha pahalı hem de uygulanmasının daha zor olduğu açıktır. Bu yüzden, kazıklı bir temelin yapılmasına karar verilmeden önce diğer çözümler de göz önünde tutulmalıdır. Kazıklı temelin yapılmasına da karar verildikten sonra çeşitli kazık dizaynları arasında en uygunu seçilmelidir. Değişik kazık projeleri hazırlamak ve bunları çözümlemek bir hayli emek ve zaman harcamayı gerektirmektedir.Bilgisayar teknolojisinin hızlı gelişimiyle birlikte kullanım olanağı artan sonlu elemanlar yöntemiyle çalışarak emek ve zaman kaybından ekonomi sağlanabilir. Bu amaçla tezimde Sonlu Elemanlar Yöntemini kullanan Lusas isimli programla tekil kazıkları inceledim. İlk olarak kazıklar hakkında bilgi verdim. Bu bilgileri kazıkların gruplandırılması, statik taşıma gücü, statik kazık formülleri, düşey tekil kazıkların yanal kuvvetlere karşı hesabı, kazığın yanal direnci, yük oturma eğrisinden göçme yükünün hesaplanması ana başlıkları altında verdim ve son olarak Lusas programıyla tekil bir kazığı çeşitli yükler altında davranışını ve zeminle etkileşimini irdeledim. XIII BEHAVIOUR OF A SINGLE PILE IN NONLINEAR SOIL MODELS SUMMARY Piles are columnar elements in a foundation which have the function of transfering load from the superstructure through weak compressible strata or through water, onto suffer or more compact and less compressible soils or onto rock. They may be required to carry uplift loads when used to support tall structures are subject to overturning forces from winds or waves. Piles used in marine structures are subjected to lareral loads from the impact of berthing ships and from waves. Combinations of vertical and horizantal loads are carried where piles are used to support retaining walls, bridge piers and abutments, and machinary foundations. The driving of bearing piles to support structures is one of the earliest example of art and science ofcivil engineer. In Britain there are numerous example of timber piling in bridge works and riverside settlements constructed by the romans. In nediaeval times, piles of oak and alder were usedin the foundations of great monasteries constructed in the fenlands of East Anglia. In China, timber piling was used by the bridge builders of the Han Dynasty (200 BC to AD 200). The carrying capacity of timber piles is limeted by the girth of natural timbers and the ability of the material to withstand driving by hammer without suffering damage due to splitting or splintering. Thus primitive rules must have been established in the earliest days of piling by which the allowable load on a pile was determined from its resistance to driving by a hammer of known height of drop. Knowledge was also accumulated regarding the durability of piles of different species of wood, and measures takento prevent decay by charring the timber or by building masonary rafts on pile heads cut off below water level. Timber, because of its strength combined with lightness, durabilityand ease of cutting and handling,remained the only material used for piling until comparatively recent times. It was replaced by concrete and steel only because these newer materials could be fabricated into units that were capable of sustaining compresive, bending and tensile forces far beyond the capacity of a timber pile of like dimensions. Concrete, in particular, was adaptable to in-situ forms of construction which facilitated the installation of piled foundations in drilled holes in situations where noise, vibration and ground heave had to be avoided.Reinforced concrete, which was developed as a structural medium in the late nineteenth and early twentieth centuries, largely replaced timber for high capacity piling for works on land. It could be precast in various structural forms to supt the imposed loading and ground conditions, and its durability was satisfactory for most soil and immersion conditions. The partial replacements of deriven precast concrete piles by numerous forms of cast-in-situ piles has been due XIVmore to development of highly efficient machines for drilling pile boreholes of large diameter and greath depth in wide range of soil and rock conditions, than to any deficiency in the performance of the precast concrete element. Stell has been used to an increasing extent for piling due to its ease of fabrication and handling and its ability to withstand hard driving. Problems of corrosion in marine structures have been overcome by the introduction of durable coatings and cathodic protection. While materials piles can be precisely specified, and their fabrication and installation can be controlled to conform to strict specification and code of practice requirements, the calculation of their load-carryingcapacity is complex matter which at the present time is based partly on theoritival concepts derived form the sciences of soil and rock mechanics, but mainly on emprical methods based on experience. Practice in calculating the ultimate carrying capacity of piles based on the principles of soil mechanics differs greatly from the applications of these principles to shallow spread foundations. In the latter case the entire area of soil supporting the foundation is exposed and can be inspected and sampled to ensurethat ists bearing characteristics conform to those deduced from the results of exploraty boreholes and soil tests. Provided that the correct constructional techniques are used the disturbance to the soil is limited to a depth of only a few centimeters below the excavation level for a spread foundation. Virtually the whole mass of soil influenced by the bearing pressure remains undisturbed and unaffected bt the constructional operations. Thus the safety factor againest general shear failure of the spread foundation and its settlement under the design working load can be predicted from a knowledge of the physical characteristics of the undisturbed soil with a degree of certainty which depends only on the complexiy of the soil stratifacation. The conditions which govern the supporting capacity of the piled foundation are quite different. No natter whether the pile is installed by driving by hammer, by jetting, by vibration, by jacking, screwing or drilling, the soil in contact with the pile face, from which the pile derives its support by skin friction, and its resistance to lateral loads, is completly disturbed by the method of installation. Similarry the soil rock beneath the toe of a pile is compressed (or sometimes loosened to an extent which may affect significantly its end-bearing resistance. Changes take place in conditions at the pile-soil interface over periods of days, months or years which materially affect the skin-friction resistance of a pile. These changes may be due to the dissipationof excess pore pressure set up by installing the pile, to the relative effects of friction and cohesion which in turn depend on the relative pile-to-soil movement, and to chemical or electro-chemical effects caused by the hardening of the concrete or the corrosion of the steel in contact wiyh soil. Where piles are installedin groups to carry heavy foundation loads, the operation of driving or drilling for adjacent piles can cause changes in the carrying capacity and load-settelment characteristics of the piles in the group yhat have already been deriven. In the present state of knowledge, the effects of various methods of pile installation on the carrying capacity and deformation characteristics cannot be calculated the strict application of soil or rock mechanics theory. The general procedure is to apply to simple empirical factors to the strength density, andcompressibility properties of the undisturbed soil or rock. The various factors which can be used depend on particular method of installation and are based on experience and on the results of field loading tests. The basis of the 'soil mechanics approach' to calculating the carrying capacity of piles is that the total resistance of the pile to compression loads is sum of two components, namely skin friction and end resistance. A pile in which the skin frictioanal component predominates is known as an friction pile, while a pile bearing on rock or some other hard incompressible material is known as an end-bearing pile. However, even if it is possible to make a reliable estimate of total pile resistance a further difficulty arises in predicting the problems involved in installing the piles to the depths indicated by the emprical or semempirical calculations. It is one problem to calculate that a precast concrete pile must be deriven to a depth of, say, 20 meters to carry safely a certain working load, but quite anather problem to dicede on the energy of the hanner required to drive the pileto this depth, and yet another problem to decide whether or not the pile will be irredeemably shattered while driving it to the required depth. In the case of driven and cast-in- place piles the ability to drive the pilling tube to the required depth and then to extract it within the pulling capacitiy of pilling rig must be correctly predicted. Bjerrum has drawn attention to the importance of time effects include the rate of applying load to a pile, and the time interval between installing and testing pile. The skin frictional resistance of a pile in clay loaded very slowly may only be one-half of that which is measured under the rate at which load is normally applied during a pile loading test. Tha slow rate of loading may correspond to that of a building under construction, yet the ability of a pile to carry its load is judged on its behaviour under a comparatively rapid loading test made only a few days after installation. The carrying capacity of a pile in sands may also diminish with time, but in spite of the importance of such time effects both in cohesive and cohesionless soilsthe only practicable way of determining the load-carrying capacity of a piled foundation is to confirm The design calculations by short-term tests on isolated single piles, and then to allow in the safety factor for any reduction in the carrying capacity with time. The effects of grouping piles can be taken into account by considering the pile group to act as a block foundation. Piles are commonly used: 1. To carry the superstructure loads into or through a soil stratum. Both vertical and laeral loads may be involved. 2. To resist uplift, or overturning, forces as for basement mats below the water table or to support tower legs subjected to overturning. 3. To compact loose, cohesionless deposits through a combination of pile volume displacement and driving vibrations. These piles may be later pulled. 4. To control settlements when spread footings or a mat is on a marginal soil or is underline by highly compressible stratum. 5. To stiffen the soil beneath machine foundations to control both amplitudes of vibration and the natural frequency of the system. 6. As an additional safety factor beneath bridge abutments and/or piers, particularly if xviscour is a potential problem. 7. In offshore construction to transmit loads above the water surface through the water and into the underlying soil. This is a case of partially embedded pilling subjected to vertical (and bucling) as well as lateral loads. Piles are sometimes used to control earth movements (as landslides). The reader should note that power poles and may outdoor sign poles may be considered as partiaaly embedded piles subject to lateral loads. Vertical loads may not be significant, altough buckling may require investigation for very tall members. A pile foundation is much more expensive than spread footings and likely to be more expensive than a mat. In any case great care should be exercised in determinig the soil properties at the site for the depth of possible interest so that it can be accurately determined that a pile foundation is needed and, if so, that neither an execisive number nor lengths are specified. A cost analysis should be made to determine whether a mat or piles are used to control the settelment at marginal soil sites, care should be taken to utilize both the existing ground and the piles in parallel so that a minimum number are required. Piles are inserted into the soil via number of methods: 1. Driving with steady succession of blows on the top of the pile using a pile hammer. This produces both considerable noise and local vibrations which may be disallowed by local codes or environmental agencies and, of course, may damage adjacent propery. 2. Driving using a vibratory device attached to the top of the pile. This is usually a relatively quiet method and driving vibrations may not be excessive. The method is more applicable in deposits with little cohesion. 3. Jacking the pile. This more applicable for short stiff members. 4. Drilling a hole and either inserting a pile into it or, more common, filling the cavity with concrete which produces a pile upon hardening. A number of methods exist for this tecnique. When a pile foundation is decided to opun, it is necessary to compute the required pile cross section and length based on the load from the superstructure, allowable stress in the pile material (usually a code value), and the in-situ soil properties. This is so that the necessary number and lengths of piles can be ordered by the foundation contractor. Dynamic formulas, pile-loda tests, or a combination are used to determine if the piles are adequaetly designed and placed. It is generally accepted that a load test is the most reliable means of determining the actual pile capacity. Pile capacity determinations are very difficult. A large number of different equations are used, and seldom will any two give the same computed capacity. Organizations which have been using a particular equation tend to stick with it particularly if a successful data base has been established. It is for the reason that a number of what are believed to be the most widely used (or currenly xviiaccepted) equations are included in this text. In a design situationone might compute the pile capacity by several equations using the required emperical factors suitably adjusted (or estimated) and observe the computed capacity. From a number of these computations some 'feel' for the probable capacity will develop so that a design recommmendation/proposal can be made. We should note that although all the pile-capacity equations are for a single pile, rarely is a single pile used; rather two or three (or more) piles are used in a group. We should further note that the soil properties which are used in the design are those from the initial soil-exploraiton program, and the soil properties which exist when the foundation is in service may be very different depending on how the piles have been placed and the number of piles in the group. The British Standard Code of Practice For Foundations (BS 8004) places piles in three categories. These are as follows. Large displecements piles copmrise solid-section piles with closed end, which are driven or jacked into the ground and thus displace soil. All types of driven and cast-in-place piles come into this category. Small displecements piles are also driven or jacked into the ground but have relatively small cross sectional area. They include rolled stell H orl sections, and pipe or box sections driven with an open end such that the soil enters the hollow section. Where these pile types plug with soil during driving they become large displacement types. Replacement piles are formed by first removing the soil by boring using wide range of drilling techniques. Concrete may be placed into an unlined or lined hole, or the lining may be withdrawn as the concrete is placed. Performed elements of timber, concrete, or steel may be placed in drilled holes. Types of piles in each of these categories can be listed as follows. Large displacement piles (driven types) 1. Timber (round or square sections, jointed or continuous). 2. Precast concrete (solid or tubular section in continuous or jointed units). 3. Prestressed concrete (solid or tubular section). 4. Steel tube (driven with closed end). 5. Steel box (driven with closed end). 6. Jacked-down stell tube with closed end. 7. Jacked-down solid concrete cylinder. Large displacement piles (driven and cast-in-place types) 1. Steel tube driven and withdrawn after placing concrete. xviii2. Precast concrete shell filled with concrete. Thin-walled stell shell driven by withdrawable mandrel and then filled with concrete. Small displacement piles 1. Prekast concrete (tubular section driven with open end). 2. Prestressed concrete (tubular section driven with open end). 3. Steel H section 4. Steel tube section (driven with open end and soil removed as required) 5. Steel box section (driven with open end and soil removed as required) Replacement piles 1. Concrete placed in hole drilled by rotary auger, baling, grabbing, airlift orreverse- circulation methods (bored and cast-in-place) 2. Tubes olaced in hole drilled as above and filled with concrete as necessary. 3. Precast concrete units placed in drilled hole. 4. Cement mortar or concrete injected into drilled hole. 5. Steel sections placed in drilled hole. 6. Stell tube drilled down XIX 99

ÖZET Bu çalışmada, esasları Winkler tarafından verilmiş olan yatak katsayısı kavramı incelenmiştir. Yatak katsayısının deneysel olarak ve diğer zemin özelliklerine bağlı olarak ampirik bağıntılarla ne şekilde elde edilebileceği anlatılmıştır. Yatak katsayısı temeli üzerine kurulmuş olan çeşitli hesap yöntemlerinden kısaca bahsedilmiş ve bu hipotezden yararlanılarak sonlu elemanlar yönteminin kullanılması ile geliştirilmiş olan bir bilgisayar programı verilmiştir. Yalak katsayısının zeminlere ait fiziksel tanımlayıcı bir özellik olmayışı sebebi ile uygulamada ortaya çıkan tereddütlerin giderilmesi amacı ile orta sıkılıkta bir kum zemin üzerine oturmuş sürekli bir temel değişik yatak katsayısı değerleri dikkate alınarak incelenmiş, yatak katsayısı değişiminin tasarımda kullanılacak moment ve ani temel oturmalarına etkisi gösterilmiştir. SUBGRADE MODULUS AND ITS APPLICATION TO FOUNDATION STRUCTURES SUMMARY Almost all problems in foundation engineering are concerned with stresses and deformations in the soil mass due to the boundary conditions and body forces. The elasticity and plasticity theories have been widely used to solve these problems. And even elasto plastic theories were utilized in order to obtain more realistic results. Nevertheless, none of the proposed methods could be succeeded at all. The reality lies behind these fails is mainly based on the soil itself which is not easily modeled by any of the theories. Soil is not a material that can be defined exactly such as a concrete, steel, plastic or any other material used in civil engineering. A lot of researcher has been dealing with not only engineering properties of soils but also the application methods of those properties to engineering systems. Because of the lack of resources and huge commercial competition, they will continue to investigate the most realistic model. The aim of this study is to describe concept of subgrade modulus, determination methods, ite relationship with the elastic properties of soil and to develop a user friendly computer program which uses concept of subgrade modulus. The main module of this computer program is relied on a computer program developed and given by Bowles [5]. A short summary of this study was mentioned below with the same sequence. The modulus of subgrade, ko, is only a conceptual relationship with the pressure and soil movement. This approach was presented by Winkler in 1867 [2], and has been widely used since then. The foundation material representation which he adopted is now called a Winkler foundation. It is also called one parameter model since it describes foundation behavior just with a proportionally constant k. Before getting into more details regarding determination and using of subgrade modulus, basic concepts of Winkler approach and recent improvements over his theory should be discussed firstly. According to Winkler theory only the loaded area settles while adjacent fields stay unchanged. So it assumes the soil as a disconnected medium. But in real situation, when a load applied to the surface of a linearly elastic half-space not only loaded area deflects but also unloaded adjacent areas moves down with diminishing displacements with distance as the soil is a connected continuum. A linearly elastic continuum is described by two material properties, Young's modulus E and Poisson's ratio t>. Someresearchers studied on disability of Winkler approach for describing soil behavior, may be the most attractive one is Vlasov and Leontiev's model. It enables deflections outside the loaded region to be effected and permits both deflections and moments to be matched. Various improvements along this line have been suggested by a number of authors including Wieghardt, Filonenko-Borodich, Hetenyi and Pasternak [2]. All their additional assumption to Winkler's, the tops of the soil springs forming the ground surface are tied together by a stretched elastic string or membrane or shear beam. The tension, S, in this string is the second soil property. Vesic showed with as a result of his experiments that Winkler model represents the behavior of soil fairly well. In this study half of the attention was paid to the determination of subgrade modulus with direct experimental studies or with using other experimental date. Soil modulus, is usually obtained with plate loading tests and laboratory experiments. And sometimes other experimental data such as Standard penetration test results or Holland penetration test results can be used to get information about value of soil modulus. As a recent development, using of a dilatometer test data proposed by Gabr, Lunne and Powell to obtain subgrade modulus was described in this study. Also, in chapter 2, a number of empirical relationships were established among subgrade modulus and elastic properties of soil and geometric structure of foundation including equations of Terzaghi, Terzaghi and Peck, Vesic, Broms, Kögler and Scheidig. The meaning of horizontal and vertical modulus was also described in the same section. If the soil response to a beam resting on its surface is that of a linear spring, then its behavior against an embedded beam or pile can be represented with two springs, one at the front and the other at the rear of the pile. This assumption ignores the shearing reactions along the pile sides. It shows that in an isotropic soil the basic subgrade reaction coefficient ko to be used in pile studies is twice the value that would be employed for the same member acting as a beam at the surface of the same soil. Concepts for constant or variable k, soil modulus was discussed more detailed in chapter 2. As a summary, for both sands and clays, the elastic modulus does not vary with the width of the piles. For stiff clay, the coefficient may be assumed to be constant with depth. And it was shown that subgrade modulus can vary with the depth of pile. Subsequent chapters are concerning with the fundamentals of finite element method, and its use for the foundation engineering together with the subgrade modulus. XIUse of elastic and plastic theories together or separately for solving foundation problems has great difficulties for practical purposes. The main disadvantages of these approaches are determining the soil structure interaction and behavior of the soil under different load cases because of the computational difficulties. The solutions to this type of problems have been obtained easily by the finite element method. According to the finite element method, soil mass is assumed as if it consists of a finite number of discrete elements interconnected at a finite number of nodal points. The properties of the elements are adjusted so that the assemblage of elements behaves in the same manner as the original continuum. Behavior of every discrete element is known with using various techniques of structural analysis. The basic steps of finite element solution can be summarized as followings; 1st step - Dividing of the continuum into finite elements, 2nd step - Building stiffness and load terms of an arbitrary element with respect to a convenient local coordinate system. 3rd step - Development of a transformation matrix ( it is also called constraint matrix) to transform the stiffness matrix from the local coordinate system to a generalized coordinate system. 4th step - Generation of the final stiffness matrix for the entire assemblage of elements, incorporating the boundary forces, body forces and deflections. 5th step - Solution of the resulting linear simultaneous equations for the unknown nodal forces. 6th step - Evaluation of subsidiary element quantities such as stresses in the displacement method. Generally, below mentioned three conditions must be satisfied in the theory of finite element analysis in order to develop the stiffness matrix equation. 1. Deformations of adjacent elements must be compatible. 2. The forces acting on a finite element must be in equilibrium. 3. The displacements of each element as a result of the applied forces must be consistent with the physical properties of the material. xuSo far, the finite element method has been defined briefly. In this study, finite element method was used to solve problems of beam on an elastic subgrade and laterally loaded piles. A combined footing can be analyzed by the conventional rigid method or beam on elastic foundation method. The second, beam on elastic foundation method was developed by Winkler for computing rail road deflections under vehicles' loads. Later, Heteny developed Winkler's equations for a load at any point along a beam measured from left end. Each method is called classical solution of beam on elastic subgrade. The most efficient technique to solve this kind of problems is the finite element method. It is easy to account for boundary conditions, beam weight and nonlinear effects, including footing separation. The classical solutions of beam on elastic foundation type problems have several disadvantages over the finite element method, such as; - Assumes weightless beam. In reality state weight is a factor when footing tends to separate from soil. - Difficult to remove soil effect when footing tends to separate from soil. - Difficult to account for boundary conditions of known rotation or deflection at selected point. - Difficult to apply multiple types of loads to a footing. - Difficult to change footing properties of moment of inertia, thickness and width of beam. - Difficult to allow to change subgrade reaction along footing. The data structure and fundamentals of given computer program were described in chapter 5, As mentioned above, program was initially developed by Bowles. The program was modified for entering data more easily and adding some abilities to control over program. Bowles originally created his program with using FORTRAN IV language. It is translated into Basic programming language and using C++ programming language to establishing menus. A working copy of programs stored in a 3.5` 1.44 Mb MS DOS formatted diskette was attached. It should be added that no special computer configuration is necessary for running this program. In chapter 6, a continuous footing problem was solved thanks to given computer program with several values of subgrade modulus. The foundation soil assumed as a medium dense sand. Minimum and maximum values of subgrade modulus for medium dense sand were taken from table 2.6. This range of values divided into four parts and results were obtained for these four values. Moment diagrams and settlement curves were shown for each result data. XlllAs a conclusion, it can be seen from the discussion in previous sections that for a uniform, homogeneous linearly elastic subgrade subjected loads applied through foundation beams, the calculation of displacements, moments and stresses involves lengthy and difficult computations. Especially when layers of material of different properties are involved, only theoretical solutions are available. Because of this situation, design engineers turned their attention to the Winkler foundation representation, since it offered simpler mathematical relations. It is shown that moments and stresses in a beam are quite independent from selected values of subgrade modulus. According to the example given here, computed moments and soil stresses did not hugely changed despite the wide selection range of subgrade modulus. So, Winkler approach is not a sensitive method to describe soil behavior and it should be used for initial design values or for the foundations which have not a great importance such as ordinary building foundations. It should be expressed that in case of a multi story building or dynamically loaded foundations, behavior of foundation has to be defined more realistic and precise form than the Winkler approach. XIV 73

ÖZET Bu çalışmada, yatay yüklü kazık, palplanş perde ve ahşap iksa problemleri çeşitli bilgisayar programları yardımıyla incelenmeye çalışılmıştır. Bunun için daha önceden elde bulunan ve sonlu elemanlar yöntemi kullanılarak geliştirilmiş olan, yatay yüklü kazık ve palplanş programlarına çeşitli alt programlar eklenerek modifiye edilmiştir. Çalışmada bilgisayar programlarının yanında teorik bilgiler de verilmeye çalışılmıştır. 2 ve 3. bölümlerde kazıklı temeller ve kazıklı temellerin taşıma gücü hakkında bilgiler verilmiş, 4. bölümde yatay yüklü kazıklar incelenmiştir. 5. bölümde palplanşlar ele alınmış, 6. bölümde ise yanal toprak basınçları hakkında bilgiler verilmiştir. 7. bölümde temel çukuru kaplama yapıları hakkında bilgi verilmiş, ayrıca ahşap iksalar için, geliştirilen bilgisayar program! kullanılarak çeşitli sonuç dosyaları elde edilmiş ve bunlar tablo ve grafikler yardımıyla gösterilmiştir. Burada çeşitli araştırmacılar tarafından (Terzaghi, Tschebotarioff, Klenner, Lehman) önerilen toprak basıncı dağılımları ele alınmış ve birbirleriyle karşılaştırılarak eğilme momenti, kesme kuvveti ve yatay deplasman bakımından değişimleri incelenmiştir. 8. bölümde bilgisayar programlarında kullanılan sonlu elemanlar yöntemi anlatılmıştır. 9. bölümde ise bilgisayar programları hakkında genel bilgiler verilmiş, veri giriş dosyalarının ne şekilde hazırlanacağı anlatılmıştır. Programların fortran dilindeki kodları, örnek giriş ve çıkış dosyaları ise ekler bölümünde gösterilmiştir. VI DESIGN OF LATERALLY LOADED PILES, SHEET PILE WALLS, FLANKING STRUTTING AND SUPPORTING TRENCHES SUMMARY Computer technology has developed more than anything in recent years. This is a good news for engineers who have to solve problems more efficiently. Today's engineers are spending more time on computers than before. Consequently solutions are getting more economical and safer. In this study, three computer programs have been developed. Using these programs, it is possible to solve some geotechnical problems. These problems are: 1) Laterally loaded piles 2) Lateral earth pressure (using Coulomb equations) 3) Sheet pile walls 4) Braced wall excavations Piles in groups are often subject to both axial and lateral loads. Early designers assumed piles could carry only axial loads with graphical methods being used to find the individual pile loads in a group. In this case a force polygon containing horizontal forces required battered piles, to carry the horizontal load a3 a component of the axial load. Sign posts, power poles, and many marine pilings represented a large class of partially embedded piles subject to lateral loads that tended to be designed as `laterally loaded poles. ` Current practice treats the full range of slender vertical (or battered) structural members, fully or partially embedded in the ground, as lateral piles. A large number of load tests have fully validated the concept of vertical piles being capable of carrying lateral loads via shear and bending rather than as `axial` loaded members. It is also common to us superposition to compute pile stresses when both axial and lateral loads are present. VIIEarly attempts to analyze a laterally loaded pile used the finite-difference method. This was used to obtain a series of nondimensional curves so that a user could enter the appropriate curve with the given lateral load and estimate the ground line deflection and maximum bending moment in the pile shaft. For obvious reasons/ only selected variations of soil modulus with depth could be input into this type of solution. The finite-difference method is not easy to program since the end and interior difference equations are not the same. The equations will also depend on whether the head is free or either translation and/or rotation is restrained. Other difficulties are encountered if the pile section is not constant, and soil stratification or other considerations require use of variable length segments. Of course, all these factors can be accounted for, but it is not very straightforward. The finite element method probably models the pile more realistically than finite difference method 3İnce both node displacement and rotation are used. This should better define the elastic curve of the pile than displacements alone as in the finite difference method. Boundary conditions are substantially easier to model both for zero displacement and/or rotation or for known values of node displacements. In the finite element method solution for lateral piles we should use the more general form of ks as ks m Ag + Bs Zn Or where there is concern that the ks profile does not increase without bound a form as ks = Ag + Bs tan x - can be used where Z= depth and B^pile width or diameter. This latter equation is not currently in computer program but can be easily added. One of these equations for ka together with the means in the program to reduce the ground line node VII!spring and to input selected soil node springs to account for lenses, voids, etc., and use of Xmax to model nonlinear effects is about as accurate a soil-pile model as can be justified by both pile loads and soil data. Even when we have a lateral pile load test to back compute the parameters As,Ba (and n) all we have are the parameters for that pile load test at that particular location on the 3ite. Substantial load test data shows that different values of ks can be obtained if several piles are tested at the same site. The site variability justifies the using of a single value of ka to Xmax rather than trying to move along a nonlinear q vs. 8 curve to obtain ks based on the current value of node displacement. Since most lateral piles are usually designed for lateral displacements on the order of 6 to 10 mm at the soil line and the pile being very much stiffer than the soil the pile flexural resistance EI dominates so that bending moments in the pile are little affected over a very large range of ks. The ground line deflections are heavily dependent on ks; however, if they are tolerable over a fairly wide range of values the use of a simple expression for k3 can be justified. On the other hand the lateral earth pressure is a significant design parameter in a number of foundation engineering problems. Retaining and sheet-pile walls, both braced and unbraced excavations, grain pressure on silo walls and bins, and earth or rock pressure on tunnel walls and other underground structures require a quantitative estimate of lateral pressure on a structural member for either a design or stability analysis. The method of plastic equilibrium as defined by the Mohr rupture envelope is most generally used for estimating the lateral pressure from earth and other materials such as grain, coal, and ore. On occasion one may use the finite-element (of the elastic continuum) method but this has several distinct disadvantages for most routine design. Pressures on tunnel liners and large buried conduits are more suitable for the finite element method than most other analyses. Earth pressures are developed during soil displacements (or strains) but until the soil is on the verge of failure, as defined by the Mohr' s rupture envelope, the stresses are indeterminate. They are also somewhat indeterminate at rupture since it is difficult to produce simultaneously everywhere a plastic IXequilibrium state in a soil mass-most times it is a progressive event. Nevertheless it is common practice to analyze this as an ideal state occurrence, both for convenience and from limitations on obtaining the necessary soil parameters with a high degree of reliability. It is a legal necessity when new construction is begun in a developed area to provide protection to the adjacent existing buildings when excavation in the new site is to any depth which may cause loss of bearing capacity, settlements, or lateral movements to existing property. New construction may include cut-and-cover work when public transportation or public utility systems are installed below ground and the depth is not sufficient to utilize tunneling operations. The new construction may include excavation from depths of 1 to perhaps 15 m or more below existing ground surface for placing of one to three or more basements and subbasements. This type of work requires installation of some kind of systems of retaining structure termed a cofferdam, braced sheeting, or slurry wall together with a means of holding the retaining structure in position. The retainina structure mav be constructed of one of the 1) Sheet piling (steel, concrete, or wood) 2) Soldier beams (or piles) with or without lagging 3) Drilled- in-place concrete piles (or piers) 4) Concrete poured in a cavity retained with slurry (a dense liquid) producing a slurry wall System to hold the retaining wall in place include: 1) Wales and struts or rakers 2) Compression rings (when excavation is relatively small in plan) 3) Tieback anchorages Sheet piling is commonly used for retaining excavations because it has the highest-strength/weight ratio, and much of the piling is reusable and can generally be easily installed either with sheet pile hammers or with vibratory driving devices.Sheet pile walls are widely used for both large and small waterfront structures ranging from small pleasure- boat launching facilities to large dock structures for ocean going ships. Piers jutting into the harbor consisting of two rows of sheet piling are widely used. Sheet piling is also used for beach erosion protection, to assist in stabilizing ground slopes, for shoring walls of trenches and other excavations, and for cofferdams. When the wall is under about 3 m in height it may be cantilevered; however, for larger wall heights it is usually anchored. There are no exact methods to analyze/design sheet pile type walls. Both field observations and laboratory model tests show that there is a complex interaction of excavation depth, wall material stiffness, and passive pressure resistance. With anchored wall there is also the anchor geometry and initial anchor prestress (or load) to further complicate the analysis. Current analysis methods may be divided into two groups : 1) Discrete element methods-in this category are finite difference and finite element approaches. 2) Classical methods-procedures which involve extremely simplifying assumptions and rigid body statics. The finite element method using beam elements is used in this study as providing the best solution since there is more realistic modeling of the wall and including wall and anchor rod flexibility as well as reasonably incorporating the soil in an interaction process with the wall. The finite difference method is not further considered as it offers no advantage over the finite element method and in fact is more difficult to use. It has the disadvantage of requiring constant length elements over the full pile length and the stiffness matrix cannot be banded. Also it is difficult to model boundary conditions of zero displacement and rotation. XI 185

b) Group-oction can also be neglected for piles driven in to clay. c) Group-oction will not be considered for piles drivon into stiff clay underlying a shoft lo yer. Pile foundations may also cause settlements and a seff- lement anlysis of a pile foundation should be made if soil conditions reqvire. The of ter important things about the pile groups is thatp pile cap desing. In general, pile caps are supposted by notless than three piles in order to maintain stability. The piles are em bedded in the pile cap an amount usually specified in the co des. Embedment is at least 150 mm in the cap and the main rein forcing bars are placed at a clear distance of 75 mm aboue the pile cut-off elevation. This means that the effec tive deptti af a pile cap is generally about 250 mm less th-im the total thickness of the pile cap. The edec distance of the exterior piles are also speci fied in the codes, and it is generally reguired that the exterior piles should have at least soomm distance from the edge of concrete for relatively small diameter piles. Also, in the sixth part results of an exensive series of computations for group settlement and deflection ratios for both a homegenous soil moss and a Gibson. Soil, are presen ted. To reduce the volume of results, attention has been ge nerally conflicted to piles that are either pinned to the pile cap (, no moment developed at pile heads ) or that are fixed in to a massive cap so that the pile headscan be consi dered as fixed ( no rotation ). For these condition, the group settlement, lateral deflection, and rotation can be simply real ted to the response of a single pile. If the center of a pile top is 150 mm or more outside the section were the diagonal shear stress is to be checked» the entire reaction of the pile should be assumed effective in producing shear on the section. The reaction from any pile located 150 mm or more inside the section, probaly contributes very little to the shear. Hence, the reaction moy be considered as zero. For indermedi- afce positions, a stroigth-1 ine interpolation is comml used. XI ÖZET Kasıklar en genel anlamıyla üzerindeki yapının yüklerini daha derinlerdeki taşıma gücü daha yüksek olan zemin veya kaya tabakasına aktarmak için kullanılan; ince, usun yapı elemanlarıdır. Kasıklar ayrıca; şevlerin sağlamlaştırılmasında kaldırma kuvvetler inin -ve yatay zemin etkilerinin karşılanmasında limanlar ve köprü ayakları gibi su içinde yapılan yapılarda ve polplanş perde yapımında da kullanılmaktadır- Kazıklar ve kazıklı temeller hakkında bilgiler ile- kazıklı temellerin hesabı için yapılmış bilgisayar programların incelendiği bu tez, yedi ana bölümden oluşmaktadır Birinci Bölümde; tezin kapsamı ve amaci verilmiştir- ikinci ve üçüncü bolümde; kazık çeşitleri ve bunların incelenmesi ile kazik tipinin seçimine ait bilgiler verilmiştir- Dördüncü bölümde; kazıklı temellerin yatay yük altındaki davranışları incelenmiştir- Beşinci bölümde; kazıklı temellerin düşey yükleme haline ait bilgiler mevcuttur. Altıncı bolümde; kazıklı temeller, grup kazık olarak incelenmiş kazıkların grup içindeki davranışları ele al inmiştir. Yedinci bölümde; Matris metodu < sonlu elemenler ) kullanılarak hazırlanmış yatay yüklü, düşey yüklü kazık ve grup kazık programları ile ilgili açıklamalar verilmiştir- Ekler bölümünde; Bilgisayar programları ve çıktıları ile sayısal uygulamalar verilmiştir. VIIb) Group-oction can also be neglected for piles driven in to clay. c) Group-oction will not be considered for piles drivon into stiff clay underlying a shoft lo yer. Pile foundations may also cause settlements and a seff- lement anlysis of a pile foundation should be made if soil conditions reqvire. The of ter important things about the pile groups is thatp pile cap desing. In general, pile caps are supposted by notless than three piles in order to maintain stability. The piles are em bedded in the pile cap an amount usually specified in the co des. Embedment is at least 150 mm in the cap and the main rein forcing bars are placed at a clear distance of 75 mm aboue the pile cut-off elevation. This means that the effec tive deptti af a pile cap is generally about 250 mm less th-im the total thickness of the pile cap. The edec distance of the exterior piles are also speci fied in the codes, and it is generally reguired that the exterior piles should have at least soomm distance from the edge of concrete for relatively small diameter piles. Also, in the sixth part results of an exensive series of computations for group settlement and deflection ratios for both a homegenous soil moss and a Gibson. Soil, are presen ted. To reduce the volume of results, attention has been ge nerally conflicted to piles that are either pinned to the pile cap (, no moment developed at pile heads ) or that are fixed in to a massive cap so that the pile headscan be consi dered as fixed ( no rotation ). For these condition, the group settlement, lateral deflection, and rotation can be simply real ted to the response of a single pile. If the center of a pile top is 150 mm or more outside the section were the diagonal shear stress is to be checked» the entire reaction of the pile should be assumed effective in producing shear on the section. The reaction from any pile located 150 mm or more inside the section, probaly contributes very little to the shear. Hence, the reaction moy be considered as zero. For indermedi- afce positions, a stroigth-1 ine interpolation is comml used. XIÖZET Kasıklar en genel anlamıyla üzerindeki yapının yüklerini daha derinlerdeki taşıma gücü daha yüksek olan zemin veya kaya tabakasına aktarmak için kullanılan; ince, usun yapı elemanlarıdır. Kasıklar ayrıca; şevlerin sağlamlaştırılmasında kaldırma kuvvetler inin -ve yatay zemin etkilerinin karşılanmasında limanlar ve köprü ayakları gibi su içinde yapılan yapılarda ve polplanş perde yapımında da kullanılmaktadır- Kazıklar ve kazıklı temeller hakkında bilgiler ile- kazıklı temellerin hesabı için yapılmış bilgisayar programların incelendiği bu tez, yedi ana bölümden oluşmaktadır Birinci Bölümde; tezin kapsamı ve amaci verilmiştir- ikinci ve üçüncü bolümde; kazık çeşitleri ve bunların incelenmesi ile kazik tipinin seçimine ait bilgiler verilmiştir- Dördüncü bölümde; kazıklı temellerin yatay yük altındaki davranışları incelenmiştir- Beşinci bölümde; kazıklı temellerin düşey yükleme haline ait bilgiler mevcuttur. Altıncı bolümde; kazıklı temeller, grup kazık olarak incelenmiş kazıkların grup içindeki davranışları ele al inmiştir. Yedinci bölümde; Matris metodu < sonlu elemenler ) kullanılarak hazırlanmış yatay yüklü, düşey yüklü kazık ve grup kazık programları ile ilgili açıklamalar verilmiştir- Ekler bölümünde; Bilgisayar programları ve çıktıları ile sayısal uygulamalar verilmiştir. VIIb) Group-oction can also be neglected for piles driven in to clay. c) Group-oction will not be considered for piles drivon into stiff clay underlying a shoft lo yer. Pile foundations may also cause settlements and a seff- lement anlysis of a pile foundation should be made if soil conditions reqvire. The of ter important things about the pile groups is thatp pile cap desing. In general, pile caps are supposted by notless than three piles in order to maintain stability. The piles are em bedded in the pile cap an amount usually specified in the co des. Embedment is at least 150 mm in the cap and the main rein forcing bars are placed at a clear distance of 75 mm aboue the pile cut-off elevation. This means that the effec tive deptti af a pile cap is generally about 250 mm less th-im the total thickness of the pile cap. The edec distance of the exterior piles are also speci fied in the codes, and it is generally reguired that the exterior piles should have at least soomm distance from the edge of concrete for relatively small diameter piles. Also, in the sixth part results of an exensive series of computations for group settlement and deflection ratios for both a homegenous soil moss and a Gibson. Soil, are presen ted. To reduce the volume of results, attention has been ge nerally conflicted to piles that are either pinned to the pile cap (, no moment developed at pile heads ) or that are fixed in to a massive cap so that the pile headscan be consi dered as fixed ( no rotation ). For these condition, the group settlement, lateral deflection, and rotation can be simply real ted to the response of a single pile. If the center of a pile top is 150 mm or more outside the section were the diagonal shear stress is to be checked» the entire reaction of the pile should be assumed effective in producing shear on the section. The reaction from any pile located 150 mm or more inside the section, probaly contributes very little to the shear. Hence, the reaction moy be considered as zero. For indermedi- afce positions, a stroigth-1 ine interpolation is comml used. XIb) Group-oction can also be neglected for piles driven in to clay. c) Group-oction will not be considered for piles drivon into stiff clay underlying a shoft lo yer. Pile foundations may also cause settlements and a seff- lement anlysis of a pile foundation should be made if soil conditions reqvire. The of ter important things about the pile groups is thatp pile cap desing. In general, pile caps are supposted by notless than three piles in order to maintain stability. The piles are em bedded in the pile cap an amount usually specified in the co des. Embedment is at least 150 mm in the cap and the main rein forcing bars are placed at a clear distance of 75 mm aboue the pile cut-off elevation. This means that the effec tive deptti af a pile cap is generally about 250 mm less th-im the total thickness of the pile cap. The edec distance of the exterior piles are also speci fied in the codes, and it is generally reguired that the exterior piles should have at least soomm distance from the edge of concrete for relatively small diameter piles. Also, in the sixth part results of an exensive series of computations for group settlement and deflection ratios for both a homegenous soil moss and a Gibson. Soil, are presen ted. To reduce the volume of results, attention has been ge nerally conflicted to piles that are either pinned to the pile cap (, no moment developed at pile heads ) or that are fixed in to a massive cap so that the pile headscan be consi dered as fixed ( no rotation ). For these condition, the group settlement, lateral deflection, and rotation can be simply real ted to the response of a single pile. If the center of a pile top is 150 mm or more outside the section were the diagonal shear stress is to be checked» the entire reaction of the pile should be assumed effective in producing shear on the section. The reaction from any pile located 150 mm or more inside the section, probaly contributes very little to the shear. Hence, the reaction moy be considered as zero. For indermedi- afce positions, a stroigth-1 ine interpolation is comml used. XIIt is not necassary that pile tops be at equal elevation in other words, X,Y,Z, coordinates any read for each piles may be o-F unequal length. A-fter solutions this programme, the vertical loaded pile programme should be run again todesign the piles. XIII 223

ÖZET Çalışma, inşaat mühendisliğinin tüm dallarında önemi ve kullanımı hızla artan geotekstiileri içermekte ve* üç bölümden meydana gelmektedir. Birinci bölümde; geotekstillerin hammaddeleri, üretim metotları ve kullanım fonksiyonları hakkında genel bilgiler özetlenmiştir. İkinci bölümde; konu ile ilgili yapılan çalışmalara örnekler verilmekte ve bu amaçla; geotekstille güçlendirilmiş şev ve dolgu yapıları üzerinde, limit denge ve sonlu elemanlar yaklaşımları kullanılarak yapılan analizlerin sonucunda geliştirilen dizayn metotları ve geotekstille güçlendirilmiş kum numuneleri üzerinde yapılan direkt kesme ve üç eksenli basınç deneylerinin sonuçları sunulmuştur. Son bölümde ise; geotekstille güçlendirilmiş bir şev, elastik olarak sonlu elemanlar programı kullanılarak incelenmiştir. İncelemede; sadece zemin ve geotekstil elastisite modülleri değiştirilerek, geotekstilsiz halde ve çeşitli geotekstil serilme hallerinde oluşan yer değiştirme ve gerilmeler hesaplanmış ve birbirileri ile mukayese edilmiştir. Mukayese sonucunda; yer değiştirme ve gerilmelerin, zemin ve geotekstil elastisite modülüne ve serilme tipine bağlı olarak nasıl değiştiği saptanmış, böylece en uygun serilme tipi ve boyunun nasıl olabileceği hakkında bilgi toplanıp, yorum yapılmıştır. iv SUMMARY A STUDY ABOUT GEOTEXTILE The use of geotextiles has developed dramatically in all construction segments, such as earthworks, foundati ons, hydraulic works, road, rail and draninage works. The success of geotextiles is due to the variety of functions that they can perform simultaneously(f iltrati - on, separation, reinforcement etc. ) and to their properties (mechanical and chemical resistance, ease of handling, cost, etc.). A precise theoretical design of the necessary geotextile parametres, like in structural engineering, is still not available, mainly because of the complexity of the soil -geotextile interactions. However, the knowledge of the different properties and behavior of the three main types of fabrics, the understanding of the functions that the geotextile will perform, and the application of criteria resulting from already 20 years field and laboratory experience will greatly simplify the selec tion. The raw materials of the geotextiles are polypropy- lene(PP), polyethylene(PE), polyester(PET) and polyami- de(PA). Polypropylene has melting point of 165 C. It tends to suffer from creep. It requires addition of a stabiliser to cope with sunlight and its melting point is too low for it to be used with hot bitumen. Polyethylene has melting point of 110 C. Therefore it is used as a binder between fibers.Polyester is resistant to all substances accuring naturally in the soil. It is not susceptible to creep under continuous loading and, with a melting point of 260 C. It can be used in contact with hot bitumen. Its stability to light is good and testing showed three months open air weathering on site does not lead to any loss of strength. Polyamide's mechanical properties are affected by soil moisture. The higher water content the higher creep. These polymers are then transformed into three forms. These forms are continuous filaments, staple fibers (fila ments cutted into 50~150 mm long fibers) and slitted films(tapes) of variable width. The manufacturing techniques of geotextile are wo- vens, nonwovens needlepunched, nonwoven thermally bonded and other(staple fibers fibers chamically bonded, knitted fabrics, composites, etc.) Woven geotextiles have a weft element along the length. Threads may be flat or circular in cross-sec tion, and produce fairly uniform rectangular openings in the mesh they form. Nonwoven geotextiles have a haphazard orientation of fibres, usually fused together by heat. These are made in one of three ways; by using a small percentage of low melting point filaments in the web to acts as an adhesive, by using core fibres with a sheat which becomes tacky on heating and melts at a lower temperature than the core of individual fibres, or in the case of thin nonwovens and by using staple fibers that can be bonded by applying pressure. The major functions of geotextiles are seperation, reinforcement, filtration and drainage. Seperation is to prevent contamination of good quality materials by fine-grained subsoil. To optimally fulfill the separation function, the geotextile should exhibit follwing properties: 1) Sufficient elongation at break, to withstand lo cally important deformations 2) High `work to break`, to oppose penetration by VIindividual elements 3) Good tear and puncture resistance, to withstand sharp aggregate elements 4>Addequate filtration characteristics, to retain fine soil particles Reinforcement is to enable concentrated forced to be evenly distributed, and to reinforce the soil mass by making it resistant to tensile stresses. To perform an adeguate reinforcement function a geotextile should have: 1) High initral modulus 2) High `work to break `(toughness ) 3) Sufficient elongation at maximum load Filtration i s to allow the water to pass through, but in the same time to retain the soil particles. To perform a long term filtration function geotextiles must have following properties: 1) Adequate maximum pore size, to prevent continuous soil piping 2) Large number of pores (percent open area), to pre vent pore blocking 3) Sufficient water permeability 4> Low sensibility to compression Drainage is to allow transport of excess the plane(thi ckness ) of the geotextile. To good drainage function, a geotextile must have: water in fulfill * a 1) High in-plane permeability (transmissi vity) 2) High resistance to compression 3) Good filter properties A numerical technique for the analysis of geotextile reinforced embankments is outlined by Rowe, Booker and Balaam. This technique permits consideration of soil-re inforcement interaction, slip at the soil -geotextile interface, plastic failure within the soil and large deformations. The applicability of the approach has been assessed by examining the observed and predicted performance of a number of reinforced embankments const ructed on soft foundations. In Rowe' s study, the application of the approach is illustrated by reference to an embankment constructed on a soft peat deposit. Finally, Rowe's study presents a practical design procedure which involves the use of simple design charts. The use of this design procedure is illustrated by means of a worked example usign a typical set of desing charts. VllArı analytical approach to geotextile reinforced slope is presented by Dov Leshchinsky. It is based on limit- equilibrium and variational extremizati on. The results indicate that the potential failure surfaces are either planar or log-spiral. The analysis utilies a reinforcing membrane sheet that is orthogonal to the radius vector defining its intersection with the slip surface. Results of a closed-form solution imply that : (1) The stronger the geotextile the deeper the failure; (2) the geotextile's elevation has little effect on the stability or on the location of the slip surface provided that failure is passing through it; (3) the presence of a geotextile increases the compressive stress over the critical slip surface, and (4) the presence of a geotextile decreases the soil's tensile stress that tends to develop near the crest. The results are presented in a convenient format of stability charts. An approach for stability analysis of geotextile reinforced earth structures over firm foundations is presented by Don Leshchinsky and Ralph H.Boedeker. This approach involves both internal and external stability analyses. The internal stability analysis is based on variational limiting equilibrium and satisfies all equi librium requirements. Two extreme inclinations of reinforcement tensile resistance are investigated ; ort hogonal to the radius defining the geotextile sheet, and horizontal, signifying the as-installed position. Although a horizontal positioning requires slightly lon ger anchorage to assure pullout resistance, the slip surface is shallower when compared to the orthogonal case. As a result, the required total embedment length is longer for the orthogonal inclination. The external stability is an extension of the bilinear wedge method and it allows a slip plane to propagate horizontally along a reinforcing sheet. The results for both the internal and external stability analyses are conveniently presented in the form of design charts. Given a slope and a design safety factor, the geotextile sheet' profile as well as their required tensile resistance can be determined utilizing these charts. The results are summarized for an experimental program involving over 450 direct shear tests of sand- polymer interfaces by T.D. O'Rourke and S. J. Druschel. The interface frictional strength was found to increase with soil density and decrease with hardness of the polymer. The shear strength characteristics were found to vary as a funtion of the type of sand, but were independent of repeated loading, at least insofar as polyethylene piping and linings are concerned. This model allows for rapid evaluation of interface frictional strength and applies to plastic piping, linings, soil strip reinforcement, and a variety of other soil -polymer systems. VlllTri axial compression tests were run to compare the stress-strain response of a sand reinforced with conti nuous, geotextile lagers as opposed to randomly disribu- ted, discrete fibers by Donald H.Gray and Talal Al-Refeai. The influence of various test parameters such as amount of reinforcement, confining stress, and inclusion modulus and surface friction were also investigated. Test results, showed that both types of reinforcement improved strength, increased the axial strain at failure, and in most cases reduced post-peak loss of strength. At very low strains (